Volume converter
Litres, pints, gallons and cups, with UK and US measures kept apart. They are not the same size.
A UK pint and a US pint are not the same drink
A UK pint is 568 ml. A US pint is 473 ml. The American one is about 17% smaller, and recipes almost never say which they mean.
Follow an American recipe using British measures and every liquid in it is out by a fifth. In a stew nobody notices; in a cake or a custard it is the difference between working and not working. Every measure on this page is labelled UK or US, and the two are never merged.
The fluid ounces disagree as well
This is the part that catches people who have already spotted the pint problem. A UK fluid ounce is 28.41 ml; a US fluid ounce is 29.57 ml. The American ounce is slightly larger, even though the American pint is much smaller.
That is possible because the pints hold different numbers of ounces: 20 in a UK pint, 16 in a US one. So you cannot scale between the systems using the pint ratio, and any conversion that tries is wrong twice.
Cups, which are worse
A US cup is 236.6 ml. A metric cup, used in Britain and Australia when cups are used at all, is 250 ml. A Japanese cup is 200 ml.
A recipe that gives a bare cup measurement and nothing else is ambiguous by about 6%, which most baking tolerates and some does not. Where a recipe gives cups alongside Fahrenheit oven temperatures, read it as American.
Common questions
- Is a UK pint the same as a US pint?
- No, and this is the commonest way a converted recipe goes wrong. A UK pint is 568 ml and a US pint is 473 ml, so the American one is about 17% smaller. A UK pint is 20 fluid ounces and a US pint is 16. Both are listed separately above and never merged.
- Why are the fluid ounces different too?
- Because they were standardised separately. A UK fluid ounce is 28.41 ml and a US one is 29.57 ml, so the US ounce is very slightly larger even though the US pint is much smaller. It follows that you cannot convert between the two systems by scaling the pint: the ounce counts differ as well.
- How much is a cup?
- In an American recipe, 236.6 ml, and that is the one listed above. British recipes that use cups usually mean a 250 ml metric cup, and Australian recipes definitely do. If a recipe gives cups without saying which, read it as American unless everything else in it is metric.
- Why is a UK gallon bigger than a US gallon?
- The UK gallon was redefined in 1824 as the volume of ten pounds of water, which came to 4.546 litres. The US kept the older wine gallon of 231 cubic inches, which is 3.785 litres. Both are still in use, which is why fuel economy figures never compare directly.