Convert length, weight, temperature, volume, area and speed instantly
This free unit converter changes values between metric and imperial units in seconds. It supports length, weight, temperature, volume, area and speed, and it shows your value in every unit of the category at once.
Use it for cooking, travel, school, DIY projects or any time you need to switch between units such as miles and kilometers, pounds and kilograms, or Celsius and Fahrenheit.
For length, weight, volume, area and speed, each unit has a factor relative to a base unit:
Temperature uses formulas instead, because the scales have different starting points:
Common examples: 1 mile = 1.60934 km, 1 kg = 2.20462 lb, 1 US gallon = 3.78541 L, 100°F ≈ 37.78°C.
Every unit in a category is compared to one base unit. To convert, multiply your value by the factor of the starting unit, then divide by the factor of the target unit. The calculator does this instantly and also shows your value in all other units of the same type.
1 kilogram equals about 2.20462 pounds. To convert kg to lb, multiply by 2.20462. To convert lb to kg, multiply by 0.453592.
Multiply the Celsius value by 9/5 and add 32. For example, 100°C = 100 × 9/5 + 32 = 212°F. To convert Fahrenheit to Celsius, subtract 32 and multiply by 5/9, so 100°F is about 37.78°C.
A US gallon is about 3.785 liters. An imperial gallon, used in the UK, is about 4.546 liters, so it is roughly 20% bigger. This converter includes both.
Kelvin is the temperature scale used in science. It starts at absolute zero, the lowest possible temperature. To convert Celsius to Kelvin, add 273.15.
It uses standard conversion factors and shows results rounded to several decimal places, which is accurate enough for everyday use, school and cooking. For engineering or scientific work, check the exact factors required by your standard.
Note: Results are rounded and intended for everyday use. For precise scientific or engineering work, verify with official standards.