Milliliters to Cups Calculator

Background.

How many cups is 500 mL of milk? That depends on which cup you mean, and the United States has two. The cup behind a Nutrition Facts serving size is exactly 240 mL, fixed by the FDA's labeling rule, 21 CFR 101.9. The cup in a traditional American measuring set is 8 US fluid ounces, and because NIST gives the fluid ounce as exactly 29.5735295625 mL, that cup is exactly 236.5882365 mL. So 500 mL comes to 2.0833 label cups or 2.1134 customary cups.

The gap is about 1.44%, or 3.41 mL per cup. Nobody will notice it in a glass of milk. In bread, where a little extra water changes how a dough handles, converting four cups drifts by 13.6 mL — almost a full tablespoon. Both results are always shown, so you can match whichever cup the recipe or label had in mind.

Recipes from countries that define their own cup, such as the 200 mL measuring cup of Japanese kitchens, are a different case: their "1 cup" is already a metric amount and needs a matching measure rather than a conversion.

What is milliliters to cups calculator?

A milliliter is one thousandth of a liter, the volume unit most of the world's recipes use. The US customary cup is half a US pint — 8 fluid ounces or 16 tablespoons — which works out to 236.5882365 mL. The legal cup of 240 mL exists for food labeling: the same FDA paragraph sets a teaspoon at 5 mL, a tablespoon at 15 mL and a fluid ounce at 30 mL, so 16 label tablespoons make one label cup. Both cups are exact by definition, so the conversion adds no error of its own.

How to use this calculator.

1. 01Type the volume in milliliters — the figure from a metric recipe, a bottle or a measuring jug.
2. 02Pick the cup type: customary if you will measure with an American cup set or are matching a US cookbook; legal if you are comparing against a serving size on a US food label.
3. 03Read the result, and glance at the other cup's figure beside it. If both round to the same mark on your measuring cup, the choice makes no practical difference for that amount.

The formula.

cups = mL ÷ c, where c is the size of one cup in milliliters: 240 for the legal cup and 236.5882365 for the customary cup. The customary figure traces back to the US gallon of 231 cubic inches, which is exactly 3.785411784 L; a gallon holds 16 cups, and 3,785.411784 ÷ 16 = 236.5882365. Volume has no offset, so 0 mL is 0 cups and doubling the milliliters doubles the cups. The two answers keep a fixed ratio of 240 ÷ 236.5882365 = 1.0144, so the customary result is always 1.44% larger than the legal one, whatever volume you enter.

A worked example.

Frequently asked questions.

References& sources.

1. [1]U.S. Food and Drug Administration. 21 CFR 101.9(b)(5)(viii) - Nutrition Labeling of Food. Statutory definition of the US legal cup as exactly 240 mL for nutrition-label serving sizes.
2. [2]National Institute of Standards and Technology. NIST Special Publication 811, 2008 Edition - Guide for the Use of the International System of Units (SI), Appendix B. Source for the US fluid ounce (29.5735295625 mL) from which the exact US customary cup factor is derived.