Unit Converter
Explain like I'm 5 (what even is this tool?)
Pick what you want to convert (length, weight, temperature, and so on). Type a number and pick the unit it's in. The tool shows you that value in every other common unit at once. No guessing which way round to do it.
Converted values
Show workings
Notes on the numbers
Length and mass conversions use the internationally agreed exact factors: one inch is exactly 0.0254 metres, one pound exactly 0.45359237 kilograms. Volume and area conversions derive from those. Temperature uses the exact formulas for °C, °F and K. Nothing here is rounded until the point of display.
UK and US imperial volumes are not the same. A US gallon is 3.785 litres; a UK gallon is 4.546 litres. Both are listed so you can pick the right one. Recipe "cup" defaults to US (237 ml) unless the recipe says otherwise.
Related calculators
Units are the scaffolding. These are the jobs they support.
Common questions
Why are UK and US imperial volumes different?
Different historical definitions. A UK gallon is 4.546 litres; a US gallon is 3.785 litres. The tool lists both.
Are the conversions exact?
Yes, to full floating-point precision. The factors are the internationally agreed exact values.
Why metric and imperial?
Because real life is mixed. Road signs in the UK are in miles; science is metric; cooking straddles both; babies are weighed in pounds and ounces. One tool, both systems.
Can you add a unit?
Ask. If it's common, it probably belongs here.