A U.S. customary cup is 8 U.S. fluid ounces, or about 237 milliliters. A metric cup, used in Australia, New Zealand and some other countries, is exactly 250 milliliters — about 6 percent larger. U.S. nutrition labels use a third figure, the legal cup of 240 milliliters. That is why a “cup” in one recipe does not always match a cup in another.
Quick conversion
| Measure | Equals |
|---|---|
| U.S. customary cup | 8 U.S. fl oz, 236.6 mL (often rounded to 237 mL) |
| U.S. legal cup (nutrition labels) | 240 mL |
| Metric cup (Australia, New Zealand and others) | 250 mL |
| Imperial cup (older U.K. recipes) | 10 imperial fl oz, about 284 mL |
| Japanese cup | 200 mL |
NIST lists the U.S. cup as 237 milliliters. The legal cup of 240 mL is a labeling convenience, not a second physical cup in most American kitchens. A metric 250 mL cup is the everyday cup in many countries that cook in cups and milliliters. See how many milliliters are in a cup for the direct U.S. answer, cups in a liter and the kitchen measurement conversion chart.
Why recipes disagree
If you bake a U.S. recipe with a 250 mL metric cup, each cup is about 13 mL high, which adds up in a batter. The safer approach is to follow the system the recipe was written in, or to weigh ingredients in grams. Older British recipes that call for a cup often meant 10 imperial fluid ounces, which is larger still. When in doubt, look for a weight in the recipe, or use a scale.
Most U.S. liquid measuring cups also print milliliters, which helps when you are following a metric recipe with American tools. Fill to the 250 mL line for a metric cup, or to the 8-ounce line for a U.S. cup, and ignore the word “cup” on the other scale. Dry measuring cups sold in the U.S. are made to the 8-ounce customary cup, so they are not a perfect 250 mL scoop.
Frequently asked questions
How many milliliters are in a U.S. cup vs. a metric cup?
A U.S. customary cup is about 237 mL. A metric cup is 250 mL. U.S. nutrition labels use a 240 mL legal cup.
Why do some sources say a cup is 240 mL or 250 mL?
240 mL is the U.S. legal cup on nutrition labels. 250 mL is the metric cup used in Australia, New Zealand and several other countries. 237 mL is the U.S. customary cup of 8 fluid ounces.
Is 240 or 237 the correct U.S. cup?
For cooking with a standard American measuring cup, use 8 fluid ounces, or about 237 mL. 240 mL is the rounded value required on U.S. nutrition labels.
Helpful kitchen tools
- OXO Good Grips Angled Measuring Jug, 250 ml — A 250-milliliter (metric cup) angled jug with metric markings.
- OXO Good Grips 1-Cup Angled Measuring Cup — A 1-cup liquid cup with U.S. and metric marks, readable from above.
- OXO Good Grips Glass Measuring Cup Set, 2-Cup and 4-Cup — A 2-cup pint cup and a 4-cup (1-quart) cup with U.S. and metric marks.
- Kitchen Conversion Chart Magnet (AKS Magnets) — An 11-by-8.5-inch fridge magnet for volume and weight conversions.
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