# DigitHelm

> 300+ free online calculators and math tools for students, teachers, engineers, and professionals. No sign-up required. All calculations run entirely in the browser.

DigitHelm is a free collection of online calculators spanning 24 subject categories: basic arithmetic, percentages, averages, fractions, unit conversions, algebra, geometry, trigonometry, calculus, statistics, financial math, number theory, physics, linear algebra, discrete math, graphing, random generators, date & time, health & fitness, chemistry, text tools, computer science, and engineering.

Every tool is free, runs offline in the browser, and requires no account or download. Each calculator includes formula explanations, worked examples, and step-by-step solutions.

Base URL: https://digithelm.com/

## Key pages

- [All Calculators](https://digithelm.com/tools/): Browse all 300+ tools organized by subject category
- [About DigitHelm](https://digithelm.com/about/): Mission, features, and privacy information
- [Contact](https://digithelm.com/contact/): Bug reports, suggestions, and partnership inquiries
- [Privacy Policy](https://digithelm.com/privacy-policy/): Data handling, Google Analytics, and AdSense usage
- [Terms of Service](https://digithelm.com/terms-of-service/): Usage terms and conditions
- [Disclaimer](https://digithelm.com/disclaimer/): Accuracy and liability information

## Category pages

- [Basic Arithmetic Calculators](https://digithelm.com/tools/basic-arithmetic/): Fundamental math operations including addition, subtraction, multiplication, and division (9 tools)
- [Percentage Calculators](https://digithelm.com/tools/percentages/): Calculate percentages, percentage changes, and related operations (5 tools)
- [Averages & Ratios Calculators](https://digithelm.com/tools/averages-ratios/): Compute means, medians, modes, ratios, and proportions (6 tools)
- [Fractions & Decimals Calculators](https://digithelm.com/tools/fractions-decimals/): Convert and calculate with fractions, decimals, and mixed numbers (3 tools)
- [Unit Conversion Calculators](https://digithelm.com/tools/unit-conversions/): Convert between units of length, weight, temperature, and more (10 tools)
- [Algebra Calculators](https://digithelm.com/tools/algebra/): Solve equations, simplify expressions, and work with variables (19 tools)
- [Geometry Calculators](https://digithelm.com/tools/geometry/): Calculate areas, volumes, perimeters, and properties of shapes (22 tools)
- [Trigonometry Calculators](https://digithelm.com/tools/trigonometry/): Work with sine, cosine, tangent, and related functions (5 tools)
- [Calculus Calculators](https://digithelm.com/tools/calculus/): Derivatives, integrals, limits, and differential equations (17 tools)
- [Statistics & Probability Calculators](https://digithelm.com/tools/statistics/): Statistical analysis, probability calculations, and data tools (23 tools)
- [Financial Math Calculators](https://digithelm.com/tools/financial/): Interest rates, loan payments, investment returns, and more (49 tools)
- [Number Theory Calculators](https://digithelm.com/tools/number-theory/): Prime numbers, factors, GCD, LCM, and other number properties (9 tools)
- [Physics Calculators](https://digithelm.com/tools/physics/): Kinematics, forces, energy, waves, electricity, and thermodynamics (43 tools)
- [Linear Algebra Calculators](https://digithelm.com/tools/linear-algebra/): Matrices, determinants, vectors, eigenvalues, and systems of equations (9 tools)
- [Discrete Math Calculators](https://digithelm.com/tools/discrete-math/): Permutations, combinations, factorials, and set operations (5 tools)
- [Graphing & Visualization Tools](https://digithelm.com/tools/graphing/): Plot and visualize mathematical equations and curves (3 tools)
- [Random Generator Tools](https://digithelm.com/tools/random-generators/): Generate random numbers, passwords, dice rolls, colors, and more (8 tools)
- [Date & Time Calculators](https://digithelm.com/tools/date-time/): Calculate ages, date differences, countdowns, and time conversions (11 tools)
- [Health & Fitness Calculators](https://digithelm.com/tools/health-fitness/): Calorie needs, body fat, heart rate zones, and fitness calculators (19 tools)
- [Chemistry Calculators](https://digithelm.com/tools/chemistry/): Molar mass, pH, molarity, dilution, and chemistry calculations (11 tools)
- [Text & Encoding Tools](https://digithelm.com/tools/text-tools/): Word count, text conversion, Base64, Morse code, and encoding tools (7 tools)
- [Computer Science Calculators](https://digithelm.com/tools/computer-science/): Bitwise operations, binary arithmetic, RGB/HEX, and CS tools (7 tools)
- [Engineering Calculators](https://digithelm.com/tools/engineering/): Voltage divider, gear ratio, beam deflection, and engineering tools (9 tools)

## Basic Arithmetic tools

- [Basic Calculator](https://digithelm.com/basic-calculator/): Free online calculator with memory functions, keyboard support, calculation history, and floating-point correction. Add, subtract, multiply, and divide instantly.
- [Exponent Calculator](https://digithelm.com/exponent-calculator/): Calculate any base raised to any power (bⁿ), find the base given a result and exponent, or solve for the exponent using logarithms. Handles negative, fractional, and zero exponents with step-by-step working.
- [Scientific Notation Calculator](https://digithelm.com/scientific-notation-calculator/): Convert numbers to and from scientific notation and perform arithmetic in scientific notation.
- [Modulo Calculator](https://digithelm.com/modulo-calculator/): Calculate the remainder of a division (modulo operation) for any two numbers.
- [Nth Root Calculator](https://digithelm.com/nth-root-calculator/): Calculate any nth root of a number including square root, cube root, and custom roots.
- [Number Sorter](https://digithelm.com/number-sorter/): Sort a list of numbers in ascending or descending order. Find min, max, sum, and average.
- [Remainder Calculator](https://digithelm.com/remainder-calculator/): Calculate the quotient and remainder of any division with full long division working shown step by step. Also computes the modulo and checks divisibility for multiple divisors at once.
- [Recipe Scaling Calculator](https://digithelm.com/recipe-scaling-calculator/): Scale any recipe up or down by servings or a custom multiplier. Convert between cups, tablespoons, teaspoons, and grams.
- [Advanced Scientific Calculator](https://digithelm.com/scientific-calculator/): A CAS-level scientific calculator with graphing, matrices, complex numbers, derivatives, integrals, statistics, and equation solving — all in one.

## Percentages tools

- [Percentage Calculator](https://digithelm.com/percentage-calculator/): Calculate percentages easily. Find what percent one number is of another, increase or decrease by a percentage, and more.
- [Percentage Change Calculator](https://digithelm.com/percentage-change-calculator/): Calculate the percentage increase or decrease between two values quickly and accurately.
- [Markup Calculator](https://digithelm.com/markup-calculator/): Calculate markup percentage, selling price, and profit margin from cost and revenue.
- [Percentage Discount Calculator](https://digithelm.com/percentage-discount-calculator/): Calculate sale price, discount amount, and savings percentage for any original price.
- [Percentage Error Calculator](https://digithelm.com/percentage-error-calculator/): Calculate the percentage error and absolute error between a measured and true value.

## Averages & Ratios tools

- [Average Calculator](https://digithelm.com/average-calculator/): Calculate the mean, median, mode, standard deviation, IQR, box plot, and more for any dataset.
- [Weighted Average Calculator](https://digithelm.com/weighted-average-calculator/): Calculate the weighted average of values with different weights.
- [Ratio Calculator](https://digithelm.com/ratio-calculator/): Simplify ratios, find equivalent ratios, and solve ratio problems.
- [Proportion Solver](https://digithelm.com/proportion-solver/): Solve proportions by finding the unknown value in a/b = c/d equations.
- [Grade Calculator](https://digithelm.com/grade-calculator/): Calculate weighted final grades, simple averages, and GPA from up to 12 assignments. Find what score you need on remaining work to hit your target grade.
- [Harmonic Mean Calculator](https://digithelm.com/harmonic-mean-calculator/): Calculate the harmonic mean of any dataset. Compare harmonic, geometric, and arithmetic means. Weighted harmonic mean mode included.

## Fractions & Decimals tools

- [Fraction Calculator](https://digithelm.com/fraction-calculator/): Add, subtract, multiply, and divide fractions and mixed numbers with LCM common denominators, cross-simplification, and full step-by-step working.
- [Fraction to Decimal Converter](https://digithelm.com/fraction-to-decimal/): Convert fractions to decimals with repeating-block detection, or convert terminating decimals back to simplified fractions.
- [Mixed Number Calculator](https://digithelm.com/mixed-number-calculator/): Add, subtract, multiply, and divide mixed numbers. Converts between mixed numbers, improper fractions, and decimals with step-by-step working.

## Unit Conversions tools

- [Unit Converter](https://digithelm.com/unit-converter/): Convert between units of length, weight, temperature, volume, and more.
- [Number Base Converter](https://digithelm.com/number-base-converter/): Convert numbers between binary, octal, decimal, and hexadecimal bases.
- [Speed Converter](https://digithelm.com/speed-converter/): Convert between mph, km/h, m/s, knots, and feet per second.
- [Temperature Converter](https://digithelm.com/temperature-converter/): Convert between Celsius, Fahrenheit, Kelvin, and Rankine temperature scales.
- [Energy Converter](https://digithelm.com/energy-converter/): Convert between 15 energy units: joules, kJ, MJ, GJ, Wh, kWh, MWh, cal, kcal, BTU, therm, ft·lb, eV, keV, MeV.
- [Pressure Unit Converter](https://digithelm.com/pressure-unit-converter/): Convert between Pascal, psi, atm, bar, mmHg, and torr pressure units.
- [Data Storage Converter](https://digithelm.com/data-storage-converter/): Convert between bits, bytes, KB, MB, GB, TB, PB and binary KiB, MiB, GiB, TiB units.
- [Fuel Efficiency Converter](https://digithelm.com/fuel-efficiency-converter/): Convert fuel efficiency between L/100km, MPG US, MPG UK, km/L, gal/100mi, and mi/L simultaneously.
- [Angle Converter](https://digithelm.com/angle-converter/): Convert angles between degrees, radians, gradians, turns, arcminutes, arcseconds, and milliradians.
- [Power Unit Converter](https://digithelm.com/power-unit-converter/): Convert between watts, kilowatts, horsepower, BTU/h, and other power units.

## Algebra tools

- [Quadratic Equation Solver](https://digithelm.com/quadratic-solver/): Solve quadratic equations (ax² + bx + c = 0) and find both real and complex roots.
- [Cubic Equation Solver](https://digithelm.com/cubic-equation-solver/): Solve cubic equations (ax³ + bx² + cx + d = 0) and find all three roots with step-by-step working, graph, and factored form.
- [Polynomial Evaluator](https://digithelm.com/polynomial-evaluator/): Evaluate any polynomial at a given value of x using Horner method.
- [Logarithm Calculator](https://digithelm.com/logarithm-calculator/): Calculate logarithms with any base. Supports natural log (ln), log base 10, and custom bases.
- [Absolute Value Equation Solver](https://digithelm.com/absolute-value-equation-solver/): Solve |ax + b| = c and |ax + b| = |cx + d| with step-by-step case analysis, verification, and formatted solutions.
- [Linear Equation Solver](https://digithelm.com/linear-equation-solver/): Solve linear equations in one variable (ax + b = c) with step-by-step solutions.
- [Systems of Equations Solver](https://digithelm.com/systems-of-equations-solver/): Solve systems of two linear equations with two unknowns using Cramer's rule.
- [Inequality Solver](https://digithelm.com/inequality-solver/): Solve linear and quadratic inequalities with step-by-step solutions.
- [Summation Calculator](https://digithelm.com/summation-calculator/): Evaluate summation expressions with custom formulas, bounds, and step values.
- [Complex Number Calculator](https://digithelm.com/complex-number-calculator/): Add, subtract, multiply, divide, and apply powers and logs to complex numbers. Shows Argand diagram, polar form, modulus, and step-by-step working.
- [Completing the Square Calculator](https://digithelm.com/completing-the-square-calculator/): Convert ax² + bx + c to vertex form a(x−h)² + k step by step. Find the vertex, axis of symmetry, and roots.
- [Synthetic Division Calculator](https://digithelm.com/synthetic-division-calculator/): Divide polynomials using synthetic division and find quotient and remainder.
- [Rational Root Theorem Calculator](https://digithelm.com/rational-root-theorem-calculator/): Find all possible rational roots of a polynomial using the Rational Root Theorem.
- [Exponent Rules Calculator](https://digithelm.com/exponent-rules-calculator/): Apply all 8 laws of exponents — product, quotient, power of a power, zero, negative, fractional, and multiple-base rules — with step-by-step working.
- [Logarithm Laws Calculator](https://digithelm.com/logarithm-laws-calculator/): Apply logarithm laws: product, quotient, power, change of base, and natural log rules.
- [Arithmetic Sequence Calculator](https://digithelm.com/arithmetic-sequence-calculator/): Find the nth term, partial sum, and common difference of any arithmetic sequence. Solve for any unknown and generate up to 1,000 terms.
- [Geometric Sequence Calculator](https://digithelm.com/geometric-sequence-calculator/): Find the nth term, partial sum, and infinite sum of any geometric sequence. Determine convergence.
- [Simplify Radicals Calculator](https://digithelm.com/simplify-radicals-calculator/): Simplify radical expressions by extracting perfect square (or nth-power) factors. Converts √72 → 6√2 and handles variables.
- [Exponential Growth & Decay Calculator](https://digithelm.com/exponential-growth-calculator/): Calculate exponential growth or decay using y = ae^(rt). Covers population growth, radioactive decay, investment compounding, and any continuous growth model.

## Geometry tools

- [Area Calculator](https://digithelm.com/area-calculator/): Calculate area and perimeter for 11 shapes: rectangle, square, circle, triangle, right triangle, trapezoid, parallelogram, rhombus, ellipse, hexagon, and sector.
- [Volume Calculator](https://digithelm.com/volume-calculator/): Calculate the volume of cubes, spheres, cylinders, cones, and other 3D shapes.
- [Perimeter Calculator](https://digithelm.com/perimeter-calculator/): Calculate the perimeter and circumference of common 2D shapes.
- [Pythagorean Theorem Calculator](https://digithelm.com/pythagorean-theorem-calculator/): Find the missing side of a right triangle using a² + b² = c².
- [Distance Calculator](https://digithelm.com/distance-calculator/): Find Euclidean, Manhattan, and Chebyshev distance between 2D or 3D points. Includes midpoint, slope, line equation, and SVG visualization.
- [Midpoint Calculator](https://digithelm.com/midpoint-calculator/): Find the midpoint between two points in 2D or 3D coordinate space.
- [Slope Calculator](https://digithelm.com/slope-calculator/): Calculate the slope of a line between two points and find the line equation.
- [Circle Calculator](https://digithelm.com/circle-calculator/): Calculate radius, diameter, circumference, and area of a circle from any known value. Supports sector angle input.
- [Surface Area Calculator](https://digithelm.com/surface-area-calculator/): Calculate surface area of cubes, spheres, cylinders, cones, and other 3D shapes.
- [Triangle Solver](https://digithelm.com/triangle-solver/): Solve any triangle given SSS, SAS, ASA, or AAS using law of sines and cosines.
- [Coordinate Geometry Calculator](https://digithelm.com/coordinate-geometry-calculator/): Calculate distance, midpoint, slope, line equation, angle, section point, and triangle area from coordinates.
- [Ellipse Calculator](https://digithelm.com/ellipse-calculator/): Calculate the area, perimeter, eccentricity, focal distance, and standard equation of any ellipse from its semi-axes.
- [Regular Polygon Calculator](https://digithelm.com/regular-polygon-calculator/): Calculate the area, perimeter, interior angles, and diagonal of any regular polygon.
- [Heron's Formula Calculator](https://digithelm.com/herons-formula-calculator/): Calculate triangle area using Heron's formula (SSS), SAS, or base-height. Shows all angles, altitudes, and triangle type.
- [Circle Sector Calculator](https://digithelm.com/circle-sector-calculator/): Calculate arc length, sector area, chord length, segment area, and perimeter of a circle sector.
- [Torus Calculator](https://digithelm.com/torus-calculator/): Calculate the volume, surface area, and other properties of a torus (donut shape).
- [Golden Ratio Calculator](https://digithelm.com/golden-ratio-calculator/): Calculate golden ratio dimensions from any measurement. Shows Fibonacci spiral convergence to φ.
- [Frustum Calculator](https://digithelm.com/frustum-calculator/): Calculate volume, slant height, lateral area, and total surface area of a frustum (truncated cone).
- [Aspect Ratio Calculator](https://digithelm.com/aspect-ratio-calculator/): Calculate aspect ratios, scale dimensions proportionally, and batch-resize images or videos without distortion.
- [Map Scale Calculator](https://digithelm.com/map-scale-calculator/): Convert between map distances and real-world distances using any map scale ratio.
- [Paint Calculator](https://digithelm.com/paint-calculator/): Calculate exactly how much paint you need for any room. Enter wall dimensions, doors, windows, and number of coats.
- [Flooring Calculator](https://digithelm.com/flooring-calculator/): Calculate flooring materials for any room shape. Choose flooring type, set waste factor, and get total square footage, boxes needed, and cost estimate.

## Trigonometry tools

- [Trigonometry Calculator](https://digithelm.com/trigonometry-calculator/): Calculate sine, cosine, tangent, and their inverses for any angle.
- [Inverse Trig Calculator](https://digithelm.com/inverse-trig-calculator/): Calculate arcsin, arccos, arctan and get angles from trig ratios.
- [Right Triangle Solver](https://digithelm.com/right-triangle-solver/): Solve any right triangle given two sides or one side and one angle.
- [Radians to Degrees Converter](https://digithelm.com/radians-degrees-converter/): Convert angles between radians and degrees instantly.
- [Unit Circle Calculator](https://digithelm.com/unit-circle-calculator/): Find exact and decimal values of sin, cos, tan, csc, sec, and cot for any angle on the unit circle.

## Calculus tools

- [Derivative Calculator](https://digithelm.com/derivative-calculator/): Compute 1st through 4th numerical derivatives of any function at any point. Shows tangent line equation, derivative table, and interactive chart.
- [Second Derivative Calculator](https://digithelm.com/second-derivative-calculator/): Compute the second derivative and determine concavity at a given point.
- [Integral Calculator](https://digithelm.com/integral-calculator/): Compute definite integrals numerically using Simpson's rule and the trapezoidal rule.
- [Limit Calculator](https://digithelm.com/limit-calculator/): Evaluate limits of functions numerically as x approaches a value from left, right, or both sides.
- [Riemann Sum Calculator](https://digithelm.com/riemann-sum-calculator/): Approximate definite integrals using left, right, midpoint, and trapezoidal Riemann sums.
- [Tangent Line Calculator](https://digithelm.com/tangent-line-calculator/): Find the equation of the tangent line to a function at a given point.
- [Newton's Method Calculator](https://digithelm.com/newtons-method-calculator/): Find roots of equations using Newton's iterative method with step-by-step convergence.
- [Arc Length Calculator](https://digithelm.com/arc-length-calculator/): Calculate arc length for any function f(x) over an interval using numerical integration, or compute a circle arc length from radius and angle.
- [Partial Derivative Calculator](https://digithelm.com/partial-derivative-calculator/): Compute partial derivatives of multivariable polynomial functions.
- [Taylor Series Calculator](https://digithelm.com/taylor-series-calculator/): Compute Taylor/Maclaurin series expansions for common functions.
- [Differential Equation Solver](https://digithelm.com/differential-equation-solver/): Solve first-order ODEs numerically using Euler, Heun, and RK4. Compare method accuracy step by step.
- [Area Between Curves Calculator](https://digithelm.com/area-between-curves-calculator/): Calculate the exact area enclosed between two functions f(x) and g(x) over any interval.
- [Volume of Revolution Calculator](https://digithelm.com/volume-of-revolution-calculator/): Calculate volumes of solids of revolution using disc and shell methods.
- [Laplace Transform Calculator](https://digithelm.com/laplace-transform-calculator/): Find Laplace transforms and inverse transforms for common functions.
- [Fourier Series Calculator](https://digithelm.com/fourier-series-calculator/): Compute Fourier coefficients aₙ and bₙ for any periodic function. Supports square wave, sawtooth, triangle, rectifiers, and custom expressions.
- [Improper Integral Calculator](https://digithelm.com/improper-integral-calculator/): Evaluate improper integrals with infinite limits or discontinuities.
- [Series Convergence Calculator](https://digithelm.com/series-convergence-calculator/): Test if an infinite series converges or diverges using ratio, root, and comparison tests.

## Statistics & Probability tools

- [Standard Deviation Calculator](https://digithelm.com/standard-deviation-calculator/): Calculate standard deviation, variance, and other statistics for a dataset.
- [Z-Score Calculator](https://digithelm.com/z-score-calculator/): Calculate z-score, percentile rank, and p-values from any data point, mean, and standard deviation.
- [Probability Calculator](https://digithelm.com/probability-calculator/): Calculate single event, multiple event, conditional, and complementary probabilities.
- [Correlation Coefficient Calculator](https://digithelm.com/correlation-calculator/): Calculate Pearson r and Spearman ρ between two datasets with p-value, R², regression line, and scatter plot.
- [Linear Regression Calculator](https://digithelm.com/linear-regression-calculator/): Find the best-fit line (y = mx + b) using least squares regression.
- [Binomial Distribution Calculator](https://digithelm.com/binomial-distribution-calculator/): Calculate binomial probability P(X=k), CDF, mean, variance, and distribution statistics for any n and p.
- [Poisson Distribution Calculator](https://digithelm.com/poisson-distribution-calculator/): Calculate Poisson probabilities for rare event modeling.
- [Chi-Square Calculator](https://digithelm.com/chi-square-calculator/): Perform chi-square goodness-of-fit and independence tests with p-value, critical value, and effect size.
- [Confidence Interval Calculator](https://digithelm.com/confidence-interval-calculator/): Calculate confidence intervals for means (z and t-test) and proportions (Wald and Wilson).
- [Sample Size Calculator](https://digithelm.com/sample-size-calculator/): Calculate the required sample size for surveys and experiments.
- [Percentile Calculator](https://digithelm.com/percentile-calculator/): Find percentile ranks and values from a dataset.
- [ANOVA Calculator](https://digithelm.com/anova-calculator/): Perform one-way ANOVA with up to 6 groups. Shows ANOVA table, exact p-value, effect size η², and group statistics.
- [Bayes' Theorem Calculator](https://digithelm.com/bayes-theorem-calculator/): Calculate posterior probability P(A|B) from prior, sensitivity, and false positive rate.
- [T-Test Calculator](https://digithelm.com/t-test-calculator/): Perform a one-sample t-test to determine if a sample mean differs significantly from a known value.
- [Variance Calculator](https://digithelm.com/variance-calculator/): Calculate population variance and sample variance from a dataset with step-by-step workings.
- [Quartile Calculator](https://digithelm.com/quartile-calculator/): Calculate Q1, Q2 (median), Q3, interquartile range (IQR), and detect outliers from data.
- [Frequency Distribution Calculator](https://digithelm.com/frequency-distribution-calculator/): Build grouped or ungrouped frequency distribution tables from raw data with charts.
- [Geometric Mean Calculator](https://digithelm.com/geometric-mean-calculator/): Calculate geometric mean for growth rates, investment CAGR, and multiplicative data.
- [Moving Average Calculator](https://digithelm.com/moving-average-calculator/): Calculate simple moving average (SMA) and exponential moving average (EMA) for time series data.
- [Effect Size Calculator](https://digithelm.com/effect-size-calculator/): Calculate Cohen's d, Hedges' g, Glass's Δ, r, and η² effect sizes from means, t-statistics, or F-statistics.
- [P-Value Calculator](https://digithelm.com/p-value-calculator/): Calculate the exact p-value from a z-score, t-statistic, chi-square statistic, or F-statistic.
- [Mean, Median & Mode Calculator](https://digithelm.com/mean-median-mode-calculator/): Calculate the mean, median, mode, range, variance, standard deviation, quartiles, and IQR for any dataset.
- [Normal Distribution Calculator](https://digithelm.com/normal-distribution-calculator/): Compute exact probabilities for any normal distribution: P(X < a), P(X > a), P(a ≤ X ≤ b), inverse CDF, and PDF.

## Financial Math tools

- [Compound Interest Calculator](https://digithelm.com/compound-interest-calculator/): Calculate compound interest with monthly contributions, solve for principal, rate, or time, and see a year-by-year growth breakdown.
- [Simple Interest Calculator](https://digithelm.com/simple-interest-calculator/): Calculate simple interest using I = P × R × T formula.
- [Loan Payment Calculator](https://digithelm.com/loan-payment-calculator/): Calculate monthly loan payments, total interest, and amortization.
- [Tip Calculator](https://digithelm.com/tip-calculator/): Calculate tip amount, total bill, and split between multiple people.
- [Mortgage Calculator](https://digithelm.com/mortgage-calculator/): Calculate monthly mortgage payments, total interest, and amortization schedule.
- [ROI Calculator](https://digithelm.com/roi-calculator/): Calculate return on investment percentage from cost and revenue.
- [Currency Converter](https://digithelm.com/currency-converter/): Convert between 35 world currencies with live daily exchange rates.
- [Depreciation Calculator](https://digithelm.com/depreciation-calculator/): Calculate annual depreciation and full amortization schedules using straight-line, double declining balance, and sum-of-years-digits methods.
- [Income Tax Calculator](https://digithelm.com/tax-calculator/): Estimate your income tax based on US federal tax brackets (2024). Calculate effective tax rate.
- [Break-Even Calculator](https://digithelm.com/break-even-calculator/): Calculate the break-even point in units and revenue from fixed costs, variable costs, and selling price.
- [Retirement Savings Calculator](https://digithelm.com/retirement-savings-calculator/): Project how much you will have at retirement based on savings rate, return, and time horizon.
- [Inflation Calculator](https://digithelm.com/inflation-calculator/): Calculate the purchasing power of money over time using historical or custom inflation rates.
- [NPV Calculator](https://digithelm.com/net-present-value-calculator/): Calculate the net present value (NPV) and profitability index of an investment.
- [Debt Payoff Calculator](https://digithelm.com/debt-payoff-calculator/): Calculate how long to pay off any debt and total interest paid. Includes avalanche and snowball strategies.
- [Savings Goal Calculator](https://digithelm.com/savings-goal-calculator/): Calculate how long to reach a savings goal or the monthly contribution needed.
- [Salary to Hourly Calculator](https://digithelm.com/salary-to-hourly-calculator/): Convert annual salary to hourly, daily, weekly, and monthly rates.
- [Hourly to Salary Calculator](https://digithelm.com/hourly-to-salary-calculator/): Convert any hourly wage to annual salary, monthly, bi-weekly, weekly, and daily pay. Includes contractor vs employee cost comparison.
- [GST / VAT Calculator](https://digithelm.com/gst-vat-calculator/): Add or remove GST/VAT from any price. Multi-item invoices with individual rates. Country presets for Australia, UK, India, Canada, and EU.
- [Bill Splitter](https://digithelm.com/tip-splitter/): Split a restaurant bill with custom tip percentage and divide equally among any number of people.
- [Annuity Calculator](https://digithelm.com/annuity-calculator/): Calculate present value, future value, required payment, or term for ordinary annuities and annuities-due. Includes perpetuity mode.
- [APR Calculator](https://digithelm.com/apr-calculator/): Calculate the Annual Percentage Rate (APR) and Effective Annual Rate (EAR) for any loan.
- [Fuel Cost Calculator](https://digithelm.com/fuel-cost-calculator/): Calculate trip fuel cost from distance, fuel efficiency, and price per litre. Supports CO2 estimate.
- [Auto Loan Calculator](https://digithelm.com/auto-loan-calculator/): Calculate your monthly car loan payment with down payment, trade-in, sales tax, and fees. Includes full amortization schedule.
- [Investment Calculator](https://digithelm.com/investment-calculator/): Project long-term investment growth with monthly contributions and lump-sum inputs. Compare conservative, moderate, and aggressive return scenarios.
- [Net Worth Calculator](https://digithelm.com/net-worth-calculator/): Calculate your net worth by listing all assets and liabilities. See Federal Reserve age benchmarks and your financial independence number.
- [Budget Calculator](https://digithelm.com/budget-calculator/): Build a monthly budget and compare your actual spending to the 50/30/20 rule.
- [Rent vs Buy Calculator](https://digithelm.com/rent-vs-buy-calculator/): Compare the true total cost of renting vs buying over any time horizon. Includes opportunity cost and break-even year.
- [Paycheck Calculator](https://digithelm.com/paycheck-calculator/): Calculate your exact take-home pay after federal income tax, FICA, state taxes, and pre-tax deductions like 401(k).
- [Home Affordability Calculator](https://digithelm.com/home-affordability-calculator/): Find the maximum home price you can afford based on income, debts, and down payment.
- [Student Loan Calculator](https://digithelm.com/student-loan-calculator/): Compare all federal student loan repayment plans with IDR calculations and PSLF tracker.
- [Mortgage Refinance Calculator](https://digithelm.com/mortgage-refinance-calculator/): Calculate your monthly savings, break-even month, and cumulative net savings from refinancing.
- [CD Calculator](https://digithelm.com/cd-calculator/): Calculate Certificate of Deposit returns with APY, compounding frequency, early withdrawal penalty, and inflation-adjusted real return.
- [Capital Gains Tax Calculator](https://digithelm.com/capital-gains-tax-calculator/): Calculate federal and state capital gains tax on investments using 2024 LTCG brackets and all 50 states.
- [Car Lease vs Buy Calculator](https://digithelm.com/car-lease-vs-buy-calculator/): Compare the true cost of leasing vs buying a car. Calculates lease payment from money factor and residual.
- [College Savings Calculator](https://digithelm.com/college-savings-calculator/): Project 4-year college costs with tuition inflation and calculate 529 savings growth.
- [FIRE Calculator](https://digithelm.com/fire-calculator/): Calculate your FIRE number using the 4% safe withdrawal rate and find your months to financial independence.
- [Dividend Calculator](https://digithelm.com/dividend-calculator/): Project dividend income with DRIP reinvestment, dividend growth rate, and price appreciation over time.
- [Social Security Calculator](https://digithelm.com/social-security-calculator/): Estimate your Social Security benefit at 62, FRA, and 70 using the 2024 PIA formula with bend points.
- [RMD Calculator](https://digithelm.com/rmd-calculator/): Calculate your Required Minimum Distribution (RMD) using the IRS Uniform Lifetime Table (2022 update).
- [401(k) & Roth IRA Calculator](https://digithelm.com/401k-roth-ira-calculator/): Compare traditional 401(k) and Roth IRA contributions side by side. Project tax-deferred vs. tax-free growth.
- [Bond Price Calculator](https://digithelm.com/bond-price-calculator/): Calculate bond price from yield to maturity, coupon rate, and maturity. Compute Macaulay and modified duration, and convexity.
- [Dollar-Cost Averaging Calculator](https://digithelm.com/dollar-cost-averaging-calculator/): Simulate dollar-cost averaging vs. lump-sum investing over any period.
- [Emergency Fund Calculator](https://digithelm.com/emergency-fund-calculator/): Calculate your ideal emergency fund size based on monthly expenses, job stability, and household risk.
- [Rental Property Calculator](https://digithelm.com/rental-property-calculator/): Analyze rental property returns with cap rate, cash-on-cash return, gross rent multiplier, NOI, and projected 10-year equity.
- [Options Pricing Calculator](https://digithelm.com/options-pricing-calculator/): Price European call and put options using the Black-Scholes model. Calculate all five Greeks.
- [Credit Card Payoff Calculator](https://digithelm.com/credit-card-payoff-calculator/): Calculate exactly when you will pay off your credit card debt and how much interest you will pay.
- [Amortization Calculator](https://digithelm.com/amortization-calculator/): Generate a complete month-by-month amortization schedule for any loan.
- [CAGR Calculator](https://digithelm.com/cagr-calculator/): Calculate compound annual growth rate (CAGR) from a beginning value, ending value, and number of years.
- [Present Value Calculator](https://digithelm.com/present-value-calculator/): Calculate the present value of a future lump sum or annuity stream using any discount rate.

## Number Theory tools

- [GCD & LCM Calculator](https://digithelm.com/gcd-lcm-calculator/): Find the GCD and LCM of up to 10 integers using the Euclidean algorithm. Shows prime factorization and step-by-step working.
- [Prime Factorization Calculator](https://digithelm.com/prime-factorization-calculator/): Find the prime factorization of any positive integer and check primality.
- [Factorial Calculator](https://digithelm.com/factorial-calculator/): Calculate standard factorial (n!), double factorial (n!!), and subfactorial (!n / derangements) with exact BigInt arithmetic.
- [Fibonacci Calculator](https://digithelm.com/fibonacci-calculator/): Find any Fibonacci number F(n) with exact BigInt arithmetic up to F(10000), generate sequences, and check if a number is Fibonacci.
- [Prime Number Checker](https://digithelm.com/prime-checker/): Check if any number is prime using an optimized trial division algorithm. Also lists factors.
- [Perfect Number Checker](https://digithelm.com/perfect-number-checker/): Check if a number is perfect, abundant, or deficient and find all its proper divisors.
- [Roman Numeral Converter](https://digithelm.com/roman-numeral-converter/): Convert between Arabic numbers and Roman numerals (I, V, X, L, C, D, M).
- [Number Sequence Calculator](https://digithelm.com/number-sequence-calculator/): Find the nth term of arithmetic, geometric, and other common sequences.
- [Digital Root Calculator](https://digithelm.com/digital-root-calculator/): Calculate the digital root (iterated sum of digits), additive persistence, and Harshad check for any integer.

## Physics tools

- [Velocity Calculator](https://digithelm.com/velocity-calculator/): Calculate velocity, distance, or time using v = d/t.
- [Acceleration Calculator](https://digithelm.com/acceleration-calculator/): Solve for acceleration, final velocity, initial velocity, time, or displacement using kinematic equations.
- [Force Calculator](https://digithelm.com/force-calculator/): Calculate force, mass, or acceleration using Newton's Second Law (F = ma). Multi-unit support.
- [Projectile Motion Calculator](https://digithelm.com/projectile-motion-calculator/): Calculate range, max height, time of flight, and trajectory.
- [Work & Energy Calculator](https://digithelm.com/work-energy-calculator/): Calculate work done, kinetic energy, potential energy, and power.
- [Momentum Calculator](https://digithelm.com/momentum-calculator/): Calculate momentum, impulse, and solve collision problems.
- [Ohm's Law Calculator](https://digithelm.com/ohms-law-calculator/): Calculate voltage, current, resistance, or power using Ohm's law (V=IR).
- [Wave Calculator](https://digithelm.com/wave-calculator/): Calculate wavelength, frequency, period, and wave speed.
- [Gravity Calculator](https://digithelm.com/gravity-calculator/): Calculate free fall height, time, and velocity. Compute gravitational force and escape velocity for any planet.
- [Ideal Gas Law Calculator](https://digithelm.com/ideal-gas-law-calculator/): Solve PV = nRT for any unknown variable.
- [Friction Calculator](https://digithelm.com/friction-calculator/): Calculate static and kinetic friction forces, normal force, or coefficient. Includes 11 material presets.
- [Pendulum Calculator](https://digithelm.com/pendulum-calculator/): Calculate the period, frequency, and length of a simple pendulum.
- [Spring Constant Calculator](https://digithelm.com/spring-constant-calculator/): Calculate spring constant, force, or displacement using Hooke's law (F = kx).
- [Coulomb's Law Calculator](https://digithelm.com/coulombs-law-calculator/): Calculate electrostatic force, charge, or distance using Coulomb's Law F = kq₁q₂/r².
- [Capacitance Calculator](https://digithelm.com/capacitance-calculator/): Calculate charge, voltage, energy stored, series/parallel equivalents, and RC time constants for capacitors.
- [Thermal Expansion Calculator](https://digithelm.com/thermal-expansion-calculator/): Calculate linear and volumetric thermal expansion of materials.
- [Pressure Calculator](https://digithelm.com/pressure-calculator/): Calculate pressure from force and area, convert pressure units, and compute fluid pressure.
- [Density Calculator](https://digithelm.com/density-calculator/): Calculate density, mass, or volume using ρ = m/V. Includes 40+ material presets and specific gravity.
- [Decibel Calculator](https://digithelm.com/decibel-calculator/): Convert between decibels, power ratios, and amplitude ratios. Combine multiple sound sources and compute distance attenuation.
- [Doppler Effect Calculator](https://digithelm.com/doppler-effect-calculator/): Calculate observed frequency shift for sound and light using classical and relativistic Doppler formulas.
- [Centripetal Force Calculator](https://digithelm.com/centripetal-force-calculator/): Solve for centripetal force, mass, velocity, or radius for circular motion.
- [Torque Calculator](https://digithelm.com/torque-calculator/): Calculate torque from force, distance, and angle of application (τ = rF sin θ).
- [Kinetic Energy Calculator](https://digithelm.com/kinetic-energy-calculator/): Calculate translational and rotational kinetic energy.
- [Potential Energy Calculator](https://digithelm.com/potential-energy-calculator/): Calculate gravitational potential energy (mgh) and elastic potential energy (½kx²).
- [Snell's Law Calculator](https://digithelm.com/snells-law-calculator/): Calculate refraction angles and critical angles for light passing between media.
- [Lens Equation Calculator](https://digithelm.com/lens-equation-calculator/): Calculate focal length, object distance, image distance, and magnification for thin lenses.
- [Half-Life Calculator](https://digithelm.com/half-life-calculator/): Calculate remaining quantity, time elapsed, half-life, and decay constant using the exponential decay formula.
- [Escape Velocity Calculator](https://digithelm.com/escape-velocity-calculator/): Calculate escape velocity, orbital speed, surface gravity, and orbital period for any celestial body.
- [Buoyancy Calculator](https://digithelm.com/buoyancy-calculator/): Calculate buoyant force using Archimedes' principle (F = ρVg). Includes float/sink status and apparent weight.
- [Heat Transfer Calculator](https://digithelm.com/heat-transfer-calculator/): Calculate heat transfer by Fourier conduction, Newton convection, Stefan-Boltzmann radiation, or Q=mcΔT.
- [Electric Power Calculator](https://digithelm.com/electric-power-calculator/): Calculate electric power from voltage, current, and resistance. Includes energy consumption in kWh and electricity cost.
- [Magnetic Force Calculator](https://digithelm.com/magnetic-force-calculator/): Calculate the magnetic force on a moving charge (Lorentz force) F = qvB sin(θ).
- [Resistor Color Code Calculator](https://digithelm.com/resistor-color-code-calculator/): Decode 4-band and 5-band resistor color codes to find resistance and tolerance.
- [Blackbody Radiation Calculator](https://digithelm.com/blackbody-radiation-calculator/): Calculate peak wavelength, total radiated power per unit area, photon energy, and Planck spectrum for any temperature.
- [Reynolds Number Calculator](https://digithelm.com/reynolds-number-calculator/): Calculate the Reynolds number to determine laminar or turbulent fluid flow.
- [Electric Field Calculator](https://digithelm.com/electric-field-calculator/): Calculate electric field strength from point charges (E = kQ/r²), parallel plates (E = V/d), and electrostatic force.
- [Sound Intensity Calculator](https://digithelm.com/sound-intensity-calculator/): Calculate sound intensity level in dB from intensity, and convert between intensity and dB.
- [Specific Gravity Calculator](https://digithelm.com/specific-gravity-calculator/): Calculate specific gravity, relative density, and compare material density to water.
- [Wave Speed Calculator](https://digithelm.com/wave-speed-calculator/): Calculate wave speed, frequency, wavelength, or period using v = fλ. Supports sound, light, and all wave types.
- [Kinematics Calculator](https://digithelm.com/kinematics-calculator/): Solve all five SUVAT kinematic equations for displacement, initial velocity, final velocity, acceleration, and time.
- [Energy Calculator](https://digithelm.com/energy-calculator/): Calculate kinetic energy, gravitational PE, elastic PE, thermal energy, and electrical energy.
- [Specific Heat Calculator](https://digithelm.com/specific-heat-calculator/): Calculate heat energy (Q), mass, specific heat capacity, or temperature change using Q = mcΔT.
- [Combined Gas Law Calculator](https://digithelm.com/combined-gas-law-calculator/): Solve the combined gas law for any unknown pressure, volume, or temperature.

## Linear Algebra tools

- [Matrix Determinant Calculator](https://digithelm.com/matrix-determinant-calculator/): Calculate the determinant of 2×2 and 3×3 matrices.
- [Matrix Multiplication Calculator](https://digithelm.com/matrix-multiply-calculator/): Multiply two matrices together with step-by-step dot products.
- [Vector Calculator](https://digithelm.com/vector-calculator/): Add, subtract, find dot product, cross product, and magnitude of vectors.
- [Matrix Inverse Calculator](https://digithelm.com/matrix-inverse-calculator/): Calculate the inverse of a 2×2 or 3×3 matrix with step-by-step elimination.
- [Eigenvalue & Eigenvector Calculator](https://digithelm.com/eigenvalue-calculator/): Calculate eigenvalues and eigenvectors for 2×2 and 3×3 matrices. Shows characteristic polynomial and diagonalization.
- [Matrix Transpose Calculator](https://digithelm.com/matrix-transpose-calculator/): Transpose matrices of any size by swapping rows and columns.
- [Matrix RREF Calculator](https://digithelm.com/matrix-rref-calculator/): Reduce any matrix to Row Reduced Echelon Form (RREF) using Gauss-Jordan elimination.
- [Matrix Calculator](https://digithelm.com/matrix-calculator/): Perform matrix addition, subtraction, multiplication, transposition, and find the determinant and inverse for matrices up to 4×4.
- [Cross Product Calculator](https://digithelm.com/cross-product-calculator/): Calculate the cross product of two 3D vectors, find the resulting vector's magnitude and unit vector.

## Discrete Math tools

- [Combination Calculator](https://digithelm.com/combination-calculator/): Calculate C(n,r) combinations without repetition, C̄(n,r) with repetition, P(n,r) permutations, and nʳ. Supports BigInt exact arithmetic for large n.
- [Permutation Calculator](https://digithelm.com/permutation-calculator/): Calculate the number of permutations where order matters (nPr).
- [Boolean Algebra Calculator](https://digithelm.com/boolean-algebra-calculator/): Evaluate Boolean expressions with AND, OR, NOT, XOR, NAND, NOR, XNOR. Generates truth tables for up to 4 variables.
- [Combinations with Repetition](https://digithelm.com/combinations-with-repetition-calculator/): Calculate multiset combinations C̄(n,r) = C(n+r−1,r) where repetition is allowed. Features stars & bars visualization.
- [Pascal's Triangle Calculator](https://digithelm.com/pascal-triangle-calculator/): Generate Pascal's triangle up to any row and expand (a + b)ⁿ using the binomial theorem.

## Graphing & Visualization tools

- [Equation Graph Generator](https://digithelm.com/equation-graph-generator/): Plot up to 3 simultaneous y = f(x) equations on a shared axis. Supports polynomials, trig, logs, exponentials. Download as PNG.
- [Parametric Curve Grapher](https://digithelm.com/parametric-curve-grapher/): Plot parametric curves defined by x(t) and y(t) and download the graph as PNG.
- [Polar Graph Generator](https://digithelm.com/polar-graph-generator/): Plot polar equations r(θ) including roses, spirals, and limaçons. Download as PNG.

## Random Generator tools

- [Random Number Generator](https://digithelm.com/random-number-generator/): Generate random integers or decimals within any range. Generate single or multiple numbers at once.
- [Random Password Generator](https://digithelm.com/random-password-generator/): Generate strong, secure random passwords with custom length and character sets.
- [Dice Roller](https://digithelm.com/dice-roller/): Roll any combination of dice including D4, D6, D8, D12, D20, D100, or fully custom sides. Supports advantage, disadvantage, and drop-lowest.
- [Random List Picker](https://digithelm.com/random-list-picker/): Enter a list of items and randomly pick one or more. Perfect for decisions, giveaways, and selections.
- [Coin Flip Simulator](https://digithelm.com/coin-flip-simulator/): Online coin flip simulator with adjustable bias, batch flipping up to 100,000 times, live statistics, and session persistence.
- [Random Color Generator](https://digithelm.com/random-color-generator/): Generate random colors with HEX, RGB, and HSL values. Copy values instantly.
- [Lottery Number Generator](https://digithelm.com/lottery-number-generator/): Generate random lottery numbers for Powerball, Mega Millions, or custom number ranges.
- [UUID Generator](https://digithelm.com/uuid-generator/): Generate UUID v4 universally unique identifiers instantly. Generate single or bulk UUIDs.

## Date & Time tools

- [Age Calculator](https://digithelm.com/age-calculator/): Calculate your exact age in years, months, days, hours, and minutes. Includes next birthday countdown and zodiac sign.
- [Date Difference Calculator](https://digithelm.com/date-difference-calculator/): Calculate the exact number of calendar days, business days, weeks, months, and years between any two dates.
- [Unix Timestamp Converter](https://digithelm.com/unix-timestamp-converter/): Convert between Unix timestamps and human-readable dates. Supports seconds and milliseconds.
- [Day of Week Calculator](https://digithelm.com/day-of-week-calculator/): Find the day of the week for any date — past, present, or future. Shows ISO week number, day of year, and quarter.
- [Work Hours Calculator](https://digithelm.com/work-hours-calculator/): Calculate total work hours between a start and end time, with optional break deductions.
- [Shift Schedule Creator](https://digithelm.com/shift-creator/): Automatically generate weekly shift schedules for any team. Download as PDF or CSV.
- [Countdown Calculator](https://digithelm.com/countdown-calculator/): Live countdown to any date with days, hours, minutes, seconds, progress bar, and saved countdowns.
- [Time Duration Calculator](https://digithelm.com/time-duration-calculator/): Add or subtract time durations. Convert hours, minutes, and seconds.
- [Business Days Calculator](https://digithelm.com/business-days-calculator/): Count working days between two dates, add or subtract business days. Supports US & UK holiday presets.
- [Time Zone Converter](https://digithelm.com/time-zone-converter/): Convert times between any of 400+ time zones. Compare multiple cities side by side and find the best meeting time across zones.
- [Week Number Calculator](https://digithelm.com/week-number-calculator/): Find the ISO week number for any date, list all weeks in a year, and calculate the date range for any given week.

## Health & Fitness tools

- [BMI Calculator](https://digithelm.com/bmi-calculator/): Calculate your BMI instantly with metric or imperial units. See weight category, BMI Prime, Ponderal Index, and healthy weight range.
- [Calorie Calculator](https://digithelm.com/calorie-calculator/): Calculate daily calories using Mifflin-St Jeor, Harris-Benedict, or Katch-McArdle. Find your TDEE and set calorie targets.
- [Body Fat Calculator](https://digithelm.com/body-fat-calculator/): Estimate body fat percentage using the US Navy circumference method. See lean mass, fat mass, and body composition category.
- [Heart Rate Zone Calculator](https://digithelm.com/heart-rate-zone-calculator/): Calculate all 5 heart rate training zones using Max HR % or Karvonen method.
- [Ideal Weight Calculator](https://digithelm.com/ideal-weight-calculator/): Calculate ideal body weight using Devine, Robinson, Miller, and Hamwi formulas.
- [Water Intake Calculator](https://digithelm.com/water-intake-calculator/): Calculate your recommended daily water intake based on weight, activity level, and climate.
- [Running Pace Calculator](https://digithelm.com/pace-calculator/): Calculate pace, speed, distance, or time for running, walking, and cycling activities.
- [Macronutrient Calculator](https://digithelm.com/macro-calculator/): Calculate your daily protein, carbohydrate, and fat targets based on your TDEE and goals.
- [BMR Calculator](https://digithelm.com/bmr-calculator/): Calculate your Basal Metabolic Rate (BMR) and Total Daily Energy Expenditure (TDEE) using multiple formulas.
- [Sleep Calculator](https://digithelm.com/sleep-calculator/): Calculate ideal bedtimes or wake-up times based on 90-minute sleep cycles.
- [TDEE Calculator](https://digithelm.com/tdee-calculator/): Calculate your Total Daily Energy Expenditure (TDEE) with macro targets using multiple formulas.
- [Pregnancy Due Date Calculator](https://digithelm.com/pregnancy-due-date-calculator/): Calculate your estimated due date from LMP, conception date, IVF transfer date, or ultrasound.
- [Ovulation Calculator](https://digithelm.com/ovulation-calculator/): Predict your fertile window and ovulation date from your cycle length and last period.
- [One-Rep Max Calculator](https://digithelm.com/one-rep-max-calculator/): Calculate your one-rep max using Epley, Brzycki, Lombardi, and O'Conner formulas.
- [Waist-to-Hip Ratio Calculator](https://digithelm.com/waist-to-hip-ratio-calculator/): Calculate your waist-to-hip ratio and see your WHO cardiovascular risk category.
- [VO2 Max Calculator](https://digithelm.com/vo2-max-calculator/): Estimate VO2 max from a 1.5-mile run, Rockport walk test, resting heart rate, or submaximal cycle test.
- [Caloric Deficit Calculator](https://digithelm.com/caloric-deficit-calculator/): Calculate the daily calorie deficit you need to reach your goal weight by a target date.
- [Calories Burned Calculator](https://digithelm.com/calories-burned-calculator/): Calculate calories burned during any exercise using MET values, body weight, and duration. Covers 40+ activities.
- [Lean Body Mass Calculator](https://digithelm.com/lean-body-mass-calculator/): Calculate lean body mass (LBM) using four clinical formulas: Boer, James, Hume, and Peters.

## Chemistry tools

- [Molar Mass Calculator](https://digithelm.com/molar-mass-calculator/): Calculate the molar mass of common chemical elements and simple compounds.
- [Molarity Calculator](https://digithelm.com/molarity-calculator/): Calculate molarity, moles, or volume of solutions using M = n/V formula.
- [pH Calculator](https://digithelm.com/ph-calculator/): Calculate pH, pOH, [H⁺], and [OH⁻] concentrations for acids and bases.
- [Dilution Calculator](https://digithelm.com/dilution-calculator/): Solve any variable in C₁V₁ = C₂V₂ and generate serial dilution tables.
- [Stoichiometry Calculator](https://digithelm.com/stoichiometry-calculator/): Convert between moles and grams using molar mass. Calculate mass from moles and vice versa.
- [Periodic Table](https://digithelm.com/periodic-table/): Explore the full periodic table with detailed element data including atomic number, mass, electron configuration, and properties.
- [Percent Yield Calculator](https://digithelm.com/percent-yield-calculator/): Calculate percent yield, theoretical yield, or actual yield for any chemical reaction with step-by-step stoichiometry.
- [Limiting Reagent Calculator](https://digithelm.com/limiting-reagent-calculator/): Find the limiting reagent, excess reactant, and theoretical yield for any balanced chemical reaction.
- [Empirical Formula Calculator](https://digithelm.com/empirical-formula-calculator/): Find the empirical formula and molecular formula from mass percentages or grams of each element.
- [Significant Figures Calculator](https://digithelm.com/sig-figs-calculator/): Count significant figures in any number, round to N sig figs, and perform arithmetic with automatic sig fig rules.
- [Henderson-Hasselbalch Calculator](https://digithelm.com/henderson-hasselbalch-calculator/): Calculate buffer pH using the Henderson-Hasselbalch equation. Includes buffer capacity and common buffer presets.

## Text & Encoding tools

- [Word Count Calculator](https://digithelm.com/word-count-calculator/): Count words, characters, sentences, paragraphs, and estimate reading time for any text.
- [Text Case Converter](https://digithelm.com/text-case-converter/): Convert text to UPPERCASE, lowercase, Title Case, Sentence case, camelCase, or snake_case.
- [Base64 Encoder & Decoder](https://digithelm.com/base64-encoder/): Encode text and files to Base64, decode Base64 strings, generate data URIs. Supports URL-safe Base64 and MIME line-wrap.
- [Morse Code Converter](https://digithelm.com/morse-code-converter/): Convert text to Morse code and decode Morse code back to text.
- [ASCII & Unicode Value Calculator](https://digithelm.com/ascii-value-calculator/): Convert any character to ASCII decimal, hex, octal, binary, and UTF-8 bytes — or decode character codes back to text.
- [Number to Words Converter](https://digithelm.com/number-to-words-converter/): Convert any number (up to trillions) to its English word representation.
- [Reading Time Calculator](https://digithelm.com/reading-time-calculator/): Estimate how long any text takes to read at average, fast, or slow reading speeds.

## Computer Science tools

- [Bitwise Calculator](https://digithelm.com/bitwise-calculator/): Perform bitwise AND, OR, XOR, NOT, left shift, and right shift on 8/16/32-bit integers. Interactive bit toggle panel.
- [Binary Arithmetic Calculator](https://digithelm.com/binary-addition-calculator/): Add, subtract, multiply, and divide binary numbers with long-form carry/borrow visualization and column-by-column step table.
- [Two's Complement Calculator](https://digithelm.com/twos-complement-calculator/): Convert integers to two's complement binary representation and back.
- [RGB to HEX Color Converter](https://digithelm.com/rgb-hex-converter/): Convert colors between RGB, HEX, and HSL formats instantly.
- [IP Subnet Calculator](https://digithelm.com/ip-subnet-calculator/): Calculate subnet mask, network address, broadcast address, and usable hosts for any CIDR.
- [Floating Point Converter](https://digithelm.com/floating-point-converter/): Convert any decimal to its IEEE 754 32-bit and 64-bit binary representation. Coloured bit display and field breakdown.
- [Bandwidth Calculator](https://digithelm.com/bandwidth-calculator/): Calculate file transfer time from file size and connection speed. Convert between all bandwidth units.

## Engineering tools

- [Voltage Divider Calculator](https://digithelm.com/voltage-divider-calculator/): Calculate output voltage from a resistor voltage divider circuit using Vout = Vin × R2/(R1+R2).
- [Gear Ratio Calculator](https://digithelm.com/gear-ratio-calculator/): Calculate gear ratio, output RPM, torque multiplier, and speed change for simple gear pairs and multi-stage gear trains.
- [Beam Deflection Calculator](https://digithelm.com/beam-deflection-calculator/): Calculate maximum deflection and slope for cantilever, simply supported, and fixed-fixed beams.
- [Pipe Flow Calculator](https://digithelm.com/pipe-flow-calculator/): Calculate fluid flow rate, velocity, and pressure drop in pipes using the Darcy-Weisbach equation.
- [Power Factor Calculator](https://digithelm.com/power-factor-calculator/): Calculate power factor, real power, reactive power, and apparent power for AC circuits.
- [Resistor Calculator](https://digithelm.com/resistor-calculator/): Calculate equivalent resistance for resistors in series, parallel, or mixed configurations.
- [Concrete Calculator](https://digithelm.com/concrete-calculator/): Calculate concrete volume for slabs, footings, walls, columns, and circular pads. Shows bags needed and optional cost estimate.
- [Wire Gauge Calculator](https://digithelm.com/wire-gauge-calculator/): Look up AWG wire gauge specs: current-carrying capacity, resistance per foot, voltage drop, and cross-sectional area.
- [Battery Life Calculator](https://digithelm.com/battery-life-calculator/): Estimate battery runtime from capacity (mAh/Wh) and current draw. Calculate charge cycles and find the right battery size.