Volume converter

Eleven units of volume including the US and imperial gallons, which differ by about twenty percent. The US customary units are used for the spoons and cups, since those are what recipes calling for cups almost always mean.

Volume has more traps than any other category. A US gallon is 3.785 litres and an imperial gallon 4.546 — a difference big enough to matter for fuel economy figures, which is why US and UK miles-per-gallon numbers are not comparable. The fluid ounce differs too, and confusingly in the opposite direction: the imperial fluid ounce is slightly *smaller* than the US one, so an imperial pint of 20 fl oz is still larger than a US pint of 16. For cooking, the cup is worse still: US 237 ml, metric 250 ml, and Japanese 200 ml, all called a cup.