Unit Converter | Length, Weight & More
Convert between units of length, weight, temperature, volume, and more.
Category
What Is the Unit Converter | Length, Weight & More?
Unit conversion reduces every measurement to a common base unit, then scales to the target. For multiplicative units (length, mass, volume, area, speed, data) the formula is simply value × (from_factor / to_factor). Temperature requires offset conversions because Fahrenheit and Rankine have non-zero offsets relative to absolute zero.
Data units deserve special attention: the International System uses SI prefixes (1 kB = 1 000 B), while computing traditionally uses binary prefixes (1 KiB = 1 024 B). This calculator uses binary convention (powers of 2) for KB/MB/GB/TB, matching how operating systems report file sizes.
Why metric vs. imperial matters in engineering
Formula
Key Conversion Factors, Common Reference Values
| Category | From | To | Factor |
|---|---|---|---|
| Length | 1 inch | 2.54 cm | × 2.54 |
| Length | 1 mile | 1.609 344 km | × 1.609344 |
| Length | 1 nautical mile | 1.852 km | × 1.852 |
| Weight | 1 pound | 453.592 g | × 453.592 |
| Weight | 1 stone | 6.350 29 kg | × 6.35029 |
| Weight | 1 US ton | 907.185 kg | × 907.185 |
| Volume | 1 US gallon | 3.785 41 L | × 3.78541 |
| Volume | 1 UK gallon | 4.546 09 L | × 4.54609 |
| Area | 1 acre | 4 046.86 m² | × 4046.86 |
| Speed | 1 knot | 1.852 km/h | × 1.852 |
| Speed | 1 Mach (ISA) | 340.29 m/s | × 340.29 |
| Data | 1 GB | 1 073 741 824 B | × 2^30 |
How to Use
- 1Select a category from the tab bar: Length, Weight, Temperature, Volume, Area, Speed, or Data.
- 2Enter the value you want to convert in the Value field.
- 3Select your source unit from the From dropdown.
- 4Select your target unit from the To dropdown.
- 5Click Convert or press Enter. The result appears instantly in the highlighted panel.
- 6Use the ⇄ Swap button to reverse the conversion direction without re-entering values.
- 7Click Show All Units to see the value expressed in every unit of the current category simultaneously.
Example Calculation
Example: Convert 100 mph to km/h and m/s
Understanding Unit Converter | Length, Weight & More
Unit conversion underpins every field of science, engineering, and trade. The metric (SI) system defines seven base units, metre, kilogram, second, ampere, kelvin, mole, and candela, and all other units are derived from them. The imperial system, still used in the United States for everyday measurement, evolved from medieval English units and has no coherent mathematical base.
Temperature is the most nuanced category because Celsius and Fahrenheit both use arbitrary zero points unrelated to absolute zero (0 K). Only Kelvin and Rankine are true ratio scales, meaning you can multiply Kelvin temperatures directly. A room at 300 K is not "twice as hot" in an intuitive sense as 150 K, but the ratio is physically meaningful for gas law calculations.
Data units have a persistent source of confusion: hard drive manufacturers use SI prefixes (1 GB = 109 bytes) to report larger numbers, while operating systems use binary prefixes (1 GiB = 230 bytes). A "1 TB" drive shows as approximately 931 GiB in Windows, not a bug, just a different prefix standard. The IEC introduced the kibibyte/mebibyte nomenclature in 1998 to resolve this, but adoption remains inconsistent.
This converter uses live browser-side calculation, no server round-trips, no data sent anywhere. All conversion factors are sourced from NIST and the BIPM SI brochure for maximum accuracy.
Frequently Asked Questions
What is the difference between a metric ton and a US ton?
- ›Metric tonne (t): exactly 1 000 kg, used in international trade and science.
- ›US short ton: 2 000 lb ≈ 907.185 kg, used in US domestic freight.
- ›UK long ton: 2 240 lb ≈ 1 016.05 kg, historical, still used in some UK industries.
- ›The metric tonne is ≈ 10.2% heavier than a US short ton.
Why are there two types of gallons (US and UK)?
- ›US gallon: 3.785 41 L, based on the Queen Anne wine gallon (1706).
- ›UK imperial gallon: 4.546 09 L, redefined in 1824 as 10 lb of water at 62 °F.
- ›Difference: the UK gallon is ≈ 20% larger than the US gallon.
- ›Fuel economy: UK MPG figures are ≈ 20% higher than US MPG for the same car.
- ›Canada uses liters; UK still uses MPG (imperial) for road fuel consumption.
What is the difference between KB and KiB?
- ›SI prefix: 1 KB = 1 000 B, 1 MB = 1 000 000 B (used by hard drive manufacturers).
- ›IEC binary prefix: 1 KiB = 1 024 B, 1 MiB = 1 048 576 B (used by OS and RAM specs).
- ›A "500 GB" hard drive shows as ~465 GiB in Windows (different prefix systems).
- ›This calculator uses binary convention (1 KB = 1 024 B) for practical engineering.
How does temperature conversion differ from other unit conversions?
- ›Linear (offset): °C = (°F − 32) × 5/9, both a scale factor and an offset.
- ›Absolute zero: 0 K = −273.15 °C = −459.67 °F = 0 R.
- ›Kelvin ↔ Rankine: purely multiplicative, K × 9/5 = R (both start at absolute zero).
- ›For temperature differences (ΔT), offsets cancel, 1 °C change = 1 K change = 1.8 °F change.
What is a nautical mile and why is it different from a statute mile?
- ›Nautical mile: 1 852 m = 1 arc-minute of latitude, directly tied to Earth's geometry.
- ›Statute mile: 1 609.344 m, historical land measure, no geometric significance.
- ›Knot: 1 nautical mile per hour, standard speed unit for aviation and maritime navigation.
- ›GPS coordinates in degrees → distance: 1° latitude ≈ 111 km = 60 nautical miles.