Volume Converter

Type a volume in any of ten units and read it in the other nine at once: millilitre, litre, cubic metre, and the US customary teaspoon, tablespoon, fluid ounce, cup, pint, quart and gallon. Every factor descends from one exact definition — the US gallon is 231 cubic inches, and the inch is exactly 25.4 mm, which makes the gallon exactly 3.785411784 litres. The customary units are exact fractions of it: one gallon is 4 quarts, 8 pints, 16 cups, 128 fluid ounces, 256 tablespoons and 768 teaspoons, and the tool shows exactly those whole numbers.

The units here are the US ones, and that matters more for cooking than for anything else. An imperial gallon is 4.54609 litres, 20% larger than the US gallon, so an imperial pint holds 568.3 mL against the US 473.2 mL. What catches people out is that the imperial fluid ounce is smaller — 28.41 mL to the US 29.57 mL — because an imperial pint is 20 fluid ounces where the US pint is 16. A recipe in pints and one in fluid ounces will therefore mistranslate in opposite directions.

There is also a second American cup. The customary cup shown here is 236.5882365 mL, but the cup used on US nutrition labels is defined as exactly 240 mL, about 1.4% larger; recipes and labels are not quoting the same measure.

Readings are shown to eight significant digits, and one detail of that is worth knowing: the decimal places are capped at eight as well, so a value smaller than one loses the tail. A gallon in cubic metres reads 0.00378541 rather than the 0.0037854118 the precision alone would allow. Anything below 0.0001 switches to exponential notation instead.