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Engineering calculators

Engineering calculators cover electrical design (voltage dividers, resistor networks, RLC circuits, power factor, wire gauge and voltage drop), mechanical and structural checks (beam deflection, stress and strain, gear ratios, pipe flow, heat exchangers), energy and environment estimates, and construction material estimators for concrete, decks, fences, roofs, tile, mulch and pools.

25 tools · Updated October 21, 2026

Showing 25 tools
Battery Life CalculatorCircuits and electrical3,000 mAh battery at 250 mA10 h 48 min
Beam Deflection CalculatorMechanical, structural and thermal4 m steel beam, 100 × 200 mm, 2 kN/m0.5 mm deflection
Carbon Footprint CalculatorEnergy and environment880 kWh/mo, 11,500 mi, 5,000 km flown10.1 t CO₂e a year
Concrete & Cement CalculatorConstruction and home projects10 × 10 ft slab, 4 in thick1.358 yd³
Deck CalculatorConstruction and home projects16 × 12 ft deck, 16 ft boards29 boards
Electricity Cost CalculatorEnergy and environmentHeater, fridge and 8 LEDs at $0.17/kWh$51.74 a month
EV Charging Cost CalculatorMore engineering tools75 kWh, 20% to 80% at $0.17/kWh$8.50 per charge
Fence CalculatorConstruction and home projects150 ft privacy fence, posts 8 ft apart21 posts, 319 boards
Gear Ratio CalculatorMechanical, structural and thermal12 teeth driving 36 at 1,800 rpm3 : 1, 600 rpm
Gravel CalculatorMore engineering tools40 × 10 ft driveway, 4 in deep5.43 yd³ (7.60 tons)
LMTD CalculatorMechanical, structural and thermalHot 150→90 °C, cold 30→80 °C, counterflowLMTD 64.87 K
Mulch CalculatorConstruction and home projects20 × 10 ft bed, 3 in of mulch1.85 yd³ (25 bags)
Pipe Flow CalculatorMechanical, structural and thermal2 L/s of water, 50 mm steel, 100 m24.54 kPa drop
Pool CalculatorConstruction and home projects32 × 16 ft pool, 3.5 to 8 ft deep22,023 gallons
Power Factor CalculatorCircuits and electrical230 V, 10 A at power factor 0.81.84 kW, 1.38 kvar
Resistor Series & Parallel CalculatorCircuits and electrical220 Ω, 330 Ω and 1 kΩ in parallel116.6 Ω
RLC Circuit CalculatorCircuits and electricalSeries RLC: 10 Ω, 10 mH, 1 µFf₀ = 1.5915 kHz
Roof CalculatorConstruction and home projects40 × 30 ft gable roof, 6/12 pitch50 bundles of shingles
Signal-to-Noise Ratio CalculatorCircuits and electrical1 mW signal over 0.001 mW noise30 dB
Solar Panel CalculatorEnergy and environment6 kW system, 4.5 peak sun hours a day8,475 kWh a year
Stress-Strain CalculatorMechanical, structural and thermal50 kN on a 20 mm steel rod159.2 MPa stress
Tile CalculatorConstruction and home projects12 × 10 ft floor, 12 × 24 in tiles65 tiles (9 boxes)
Voltage Divider CalculatorCircuits and electrical12 V across 10 kΩ and 10 kΩ6 V out
Voltage Drop CalculatorCircuits and electrical16 A at 120 V, 100 ft of 12 AWG6.322 V (5.27%)
Wire Gauge CalculatorCircuits and electrical30 A load on copper wire10 AWG copper

Which one do I need?

I need two resistor values to get a specific output voltageVoltage Divider CalculatorI want the total resistance of resistors in series or parallelResistor Series & Parallel CalculatorI need to choose a wire size for a circuit run and keep voltage drop in checkVoltage Drop CalculatorI want to know how long a battery will power a deviceBattery Life CalculatorI want to know how much a beam will sag under loadBeam Deflection CalculatorI need to know how much concrete to order for a slab or footingConcrete & Cement CalculatorI want to know how many tiles to buy for a floor or wallTile CalculatorI want to estimate the payback period of a solar panel systemSolar Panel Calculator

Electrical design basics

Most low-voltage circuit questions come down to Ohm's law and how resistances combine: in series they add, and in parallel the reciprocals add. The Voltage Divider and Resistor Series and Parallel calculators handle these, and the RLC Circuit Calculator adds inductors and capacitors for resonance and impedance problems.

For building wiring, conductor size is driven by two limits: ampacity (how much current the wire can carry safely) and voltage drop over the length of the run. An informational note in the US National Electrical Code suggests keeping drop to about 3% on a branch circuit and 5% overall. The Wire Gauge and Voltage Drop calculators check both, and the Power Factor Calculator explains why AC loads draw more current than their real power alone suggests.

Mechanical and structural checks

Stress is force per unit area, strain is the resulting fractional change in length, and within the elastic range they are proportional through Young's modulus. The Stress-Strain Calculator applies this, and the Beam Deflection Calculator uses standard formulas for simply supported and cantilever beams. Deflection limits, often expressed as span divided by a number such as 360, are frequently what decides a beam size rather than strength.

Gear ratios trade speed for torque: halving the output speed roughly doubles the torque, minus losses. The Pipe Flow Calculator applies the Darcy-Weisbach equation for pressure loss, and the LMTD Calculator sizes heat exchangers from inlet and outlet temperatures.

Estimating materials for home projects

Construction estimators convert dimensions into the units materials are sold in: cubic yards of concrete or mulch, squares of roofing (100 square feet each), boxes of tile and counts of boards, posts and panels. A cubic yard is 27 cubic feet, so a 10 by 10 foot slab 4 inches thick needs about 1.23 cubic yards before waste.

Always add a waste allowance for cuts, spillage and uneven ground, and round up to whole bags, boxes or truckloads. The Concrete, Deck, Fence, Roof, Tile and Mulch calculators each include this step, and the Pool Calculator estimates water volume for chemical dosing.

Questions people ask

Real materials, loads and workmanship vary from the values used in calculations. A safety factor makes the design capacity larger than the expected load to cover that uncertainty. The appropriate factor depends on the application, the consequences of failure and the governing code.

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