Unit Converter
Length, weight and volume, metric and imperial, with the same measurement shown in every unit at once. Nothing is uploaded.
| Unit | Value |
|---|
How to use it
- Pick length, weight or volume. The unit lists change with it.
- Type the amount and choose the two units.
- The table on the right shows the same measurement in every unit of that kind, which saves converting twice.
Most of these conversions are exact
They are not measurements, they are definitions agreed in 1959, so there is no rounding error hiding anywhere:
| 1 of these | is exactly |
|---|---|
| inch | 2.54 cm |
| foot | 30.48 cm |
| yard | 0.9144 m |
| mile | 1,609.344 m |
| pound | 0.453 592 37 kg |
| nautical mile | 1,852 m |
Any figure this page shows to several decimals is therefore the genuine value, not an approximation that got away from someone.
US and imperial are different systems
They share names and not much else. A US gallon is 3.785 litres while an imperial gallon is 4.546, about twenty percent more. Pints and fluid ounces split the same way. A recipe or a fuel figure that just says gallon is ambiguous until you know where it was written, so both are listed separately here rather than quietly picking one.
Cooking measures are the worst of it
A US cup is 236.6 ml and a metric cup, used across India and Australia, is a round 250 ml. That is a six percent difference, which a curry will forgive and a cake will not.
Where a recipe gives a weight as well as a volume, use the weight. A cup of flour can vary by twenty percent depending on whether it was scooped or spooned, and no converter can fix that.
Frequently asked questions
How many centimetres are in an inch?
Exactly 2.54, and exactly is the right word. Since 1959 the inch has been defined as 2.54 centimetres by agreement rather than measured, so the conversion carries no rounding error at all. A foot is therefore exactly 30.48 centimetres.
Is a US gallon the same as an imperial gallon?
No, and the gap is large. A US gallon is 3.785 litres while an imperial gallon is 4.546 litres, about twenty percent more. Both are listed separately here for that reason. The same split affects pints and fluid ounces, so a recipe that just says pint is ambiguous unless you know where it was written.
Why does a cup in my recipe not match?
Because there are two cups in common use. A US cup is 236.6 millilitres and a metric cup, used in India and Australia, is a round 250 millilitres. Both are in the list. For baking the difference is enough to matter, so weigh the ingredient if the recipe gives a weight.
Is anything I type sent anywhere?
No. The arithmetic happens in JavaScript inside your own browser. Nothing is uploaded and nothing is saved - close the tab and it is gone.