Conversion Chart Guide
Instantly convert length, weight, volume and temperature between metric and imperial units, with quick-reference conversion charts for everyday use.
Convert Any Unit
Pick a measurement type, enter your value, choose the units to convert between, and get an instant, accurate result across metric and imperial systems.
Unit Converter
Convert length, weight, volume or temperature.
Understanding Unit Conversion
Key concepts for accurate conversions
Metric vs Imperial
The metric system scales in multiples of ten (mm, cm, m, km), while imperial units like inches, feet and miles use varying, non-decimal conversion factors.
Base Units & Prefixes
Metric prefixes such as milli-, centi- and kilo- multiply or divide a base unit by powers of ten, making mental conversions within the metric system much easier.
Temperature Is Different
Unlike length or weight, temperature scales don’t share a common zero point, so converting between Celsius, Fahrenheit and Kelvin requires addition or subtraction, not just multiplication.
Common Everyday Uses
Unit conversion comes up constantly — in cooking and recipes, travel distances, DIY measurements, fitness tracking, and reading weather forecasts from other countries.
Common Conversion Factors
The most frequently used metric-to-imperial conversion factors, rounded to three decimal places.
| Category | Unit | Equals |
|---|---|---|
| 1 inch | 2.54 cm | |
| 1 foot | 0.305 m | |
| 1 mile | 1.609 km | |
| 1 pound (lb) | 0.454 kg | |
| 1 stone | 6.350 kg | |
| 1 ounce (oz) | 28.350 g | |
| 1 UK gallon | 4.546 litres | |
| 1 US gallon | 3.785 litres | |
| 1 UK pint | 0.568 litres | |
| 0°C | 32°F / 273.15 K | |
| 100°C | 212°F / 373.15 K |
Conversion FAQ
Answers to the most frequently asked questions about unit conversion.
To convert Celsius to Fahrenheit, multiply the Celsius value by 9/5 and add 32. For example, 20°C multiplied by 1.8 is 36, plus 32 gives 68°F.
The metric system is based on units of ten, such as millimetres, metres and kilometres, making conversions straightforward. The imperial system uses units like inches, feet, and miles, with less consistent conversion factors between them.
The UK (imperial) gallon and the US gallon were standardised separately and are different sizes. A UK gallon is approximately 4.546 litres, while a US gallon is approximately 3.785 litres.
Most online converters use standard, internationally recognised conversion factors and are accurate for everyday use. For scientific, legal or medical purposes, it’s best to use the precise defined conversion factor for your specific context.
Many conversion factors, such as 1 inch to centimetres, are exact, but the decimal result is often rounded for readability. For most everyday purposes, two or three decimal places is more than accurate enough.