Unit Converter
Length, weight, volume & temperature ยท By Stuart Mathieson · Updated October 2026
Result
How the unit converter works
For length, weight and volume, the converter turns your value into a base unit - meters, kilograms or liters - and then into the unit you want. For example, 5 miles is 5 × 1,609.344 = 8,046.72 meters, which is 8.04672 kilometers.
The conversion factors are the exact definitions of the US customary units, as published by NIST: one inch is exactly 2.54 cm and one pound exactly 0.45359237 kg.
| Unit | Exact value |
|---|---|
| 1 inch | 2.54 cm |
| 1 foot | 0.3048 m |
| 1 yard | 0.9144 m |
| 1 mile | 1,609.344 m |
| 1 ounce | 28.349523125 g |
| 1 pound | 0.45359237 kg |
| 1 stone (14 lb) | 6.35029318 kg |
| 1 US gallon (231 cubic inches) | 3.785411784 L |
| 1 US cup | 236.5882365 mL |
| 1 US fluid ounce | 29.5735295625 mL |
Temperature
Temperature scales don't share a zero point, so they use formulas rather than a single factor:
For example, 37 °C is 98.6 °F, 100 °F is 37.78 °C, and −40 is the same in both Celsius and Fahrenheit.
US and imperial measures
The volume units here are US measures. The UK imperial gallon is larger - 4.54609 liters, about 20% more than a US gallon - and imperial pints and fluid ounces differ too. Recipes from some countries, such as Australia, use a metric cup of 250 mL rather than the US cup of about 237 mL.
Ounces and pounds here are the avoirdupois units used for everyday weights. A stone, still used for body weight in the UK and Ireland, is 14 pounds.
Frequently asked questions
Which unit categories are supported?
Length, weight/mass, volume, and temperature. Each category has its own list of common metric and imperial units to convert between.
How accurate are the conversions?
Conversions use standard, widely accepted conversion factors (for example 1 inch = 2.54 cm exactly) and are shown to several decimal places for precision.
Why is temperature handled differently?
Celsius, Fahrenheit, and Kelvin use different zero points, not just a scaling factor, so they need their own conversion formulas rather than a simple multiplier.
How many kilograms are in a pound?
Exactly 0.45359237 kilograms, so 1 kilogram is about 2.2046 pounds.
Sources
- Handbook 44, Appendix C: General Tables of Units of Measurement - National Institute of Standards and Technology
- Unit Conversion - National Institute of Standards and Technology