Four cups, four sizes
- US customary cup, 236.5882365 mL. Half a US liquid pint, or 8 US fluid ounces (NIST Handbook 44). US measuring cup sets are made to this size.
- US legal cup, 240 mL. Used only for nutrition labels. 21 CFR 101.9 says that "a cup means 240 mL" when a label lists a serving size.
- Metric cup, 250 mL. Used in Australia, New Zealand and Canada.
- Imperial cup, 284.130625 mL. Half an imperial pint, found in older British cookbooks. Rare today.
| Cups | US cup (mL) | US legal cup (mL) | Metric cup (mL) | Imperial cup (mL) |
|---|---|---|---|---|
| 1/4 cup | 59.1 | 60 | 62.5 | 71 |
| 1/3 cup | 78.9 | 80 | 83.3 | 94.7 |
| 1/2 cup | 118.3 | 120 | 125 | 142.1 |
| 2/3 cup | 157.7 | 160 | 166.7 | 189.4 |
| 3/4 cup | 177.4 | 180 | 187.5 | 213.1 |
| 1 cup | 236.6 | 240 | 250 | 284.1 |
| 2 cups | 473.2 | 480 | 500 | 568.3 |
| 4 cups | 946.4 | 960 | 1,000 | 1,137 |
Does the difference matter?
For a single cup, the US and metric cups differ by 13.4 mL, under a tablespoon. NIST's kitchen guidance says historic metric cup and spoon measures can often be used interchangeably with US ones. Where it starts to matter is a recipe with several cups of flour: three metric cups are 750 mL against 709.8 mL for three US cups, a difference of about 2 3/4 tablespoons, which is worth correcting in baking.
The imperial cup is a bigger jump. At 284.1 mL it is 1.2 US cups. A pre-metric British recipe read with American cups comes out short by about a sixth.
Cups of dry ingredients
This converter turns cups into millilitres, which is volume. A cup of flour and a cup of sugar have the same volume and very different weights. To turn cups into grams, use the grams to cups converter, which applies a published weight for each ingredient.
Cups and spoons
A US cup holds 16 US tablespoons or 48 teaspoons. A metric cup holds 16 2/3 metric tablespoons of 15 mL, or 12 1/2 Australian tablespoons of 20 mL. When the converter's result is a volume, it also writes it in US cups and spoons, rounded to the nearest 1/8 teaspoon. A metric cup comes out as 1 cup + 2 3/4 tsp in US measures.
| Unit | Exact size | Definition | Source |
|---|---|---|---|
| US fluid ounces | 29.5735295625 mL | 1 US fluid ounce = 1/128 US gallon | NIST Handbook 44 (2019) |
| UK | 28.4130625 mL | 1 fluid ounce = 1/20 pint | Weights and Measures Act 1985 |
| US cups | 236.5882365 mL | 1 cup = 8 US fluid ounces = 1/2 liquid pint | NIST Handbook 44 (2019) |
| US legal cups | 240 mL | For US nutrition labels, a cup means 240 mL | 21 CFR 101.9(b)(5)(viii) |
| Metric cups | 250 mL | Metric cup used in Australia, Canada and New Zealand | Wikipedia |
| Imperial cups | 284.130625 mL | Half an imperial pint, the cup in older British recipes | Weights and Measures Act 1985 |
| US pints | 473.176473 mL | 1 liquid pint = 16 US fluid ounces | NIST Handbook 44 (2019) |
| UK | 568.26125 mL | 1 pint = 0.56826125 cubic decimetre | Weights and Measures Act 1985 |
| US gallons | 3785.411784 mL | 1 US gallon = 231 cubic inches = 3.785411784 L | NIST Handbook 44 (2019) |
| UK gallons | 4546.09 mL | 1 gallon = 4.54609 cubic decimetres | Weights and Measures Act 1985 |