US Cups, Metric Cups & Cup Sizes
Not all cups hold the same volume. Here's how the common cup standards differ.
240 ml
US cup
236.6 ml
US customary cup
250 ml
Metric cup
Cup standards compared
| Cup standard | Volume (ml) | Common region | Notes |
|---|---|---|---|
| US legal cup | 240 ml | United States (nutrition labeling) | Used on US nutrition facts labels — and this site's default calculator standard. |
| US customary cup | 236.6 ml | United States (traditional recipes) | The traditional US customary measuring cup; very close to the US legal cup. |
| Metric cup | 250 ml | Australia, New Zealand, UK recipes | Common wherever recipes use the metric system; noticeably larger than the US cup. |
| Imperial cup | 284 ml | United Kingdom (historical) | Rarely used in modern UK recipes, but still turns up in older cookbooks. |
| Japanese cup | 200 ml | Japan | The standard measuring cup used in Japanese recipes. |
How much does it change results?
1 cup of flour is 120g measured with a US cup, but about 125g measured with a metric cup. Same instruction, different weight in your bowl.
| Cup standard | 1 cup of flour |
|---|---|
| US cup / 240 ml | 120g |
| US customary cup / 236.6 ml | 118.3g |
| Metric cup / 250 ml | 125g |
Which cup should you use?
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Follow your recipe's origin: a US cookbook or blog almost always means the US cup; an Australian, New Zealand, or UK recipe usually means the metric cup.
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When you're not sure which cup a recipe means, use the US cup (240 ml) — it's the most common default and the one this calculator uses unless you change it.
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For the most precise baking results — bread, macarons, laminated dough — weigh ingredients on a kitchen scale instead of relying on any cup measurement.
Frequently asked questions
Is a US cup the same as a metric cup?
No. A US cup is 240 ml (or 236.6 ml for the traditional US customary cup), while a metric cup is 250 ml — about 4% larger. For dense ingredients that difference adds up over multiple cups.
Which cup size does this calculator use?
By default we use the US cup (240 ml), the standard used on US nutrition labels. You can switch to the US customary cup or metric cup from the calculator's cup-type selector.
Does the cup size really change my baking results?
Yes. 1 cup of flour is 120g measured with a US cup, but about 125g measured with a metric cup — the same "1 cup" instruction, a different weight.
What if my recipe doesn't say which cup it means?
Guess from where the recipe is from, or better yet, weigh your ingredients with a kitchen scale so the cup standard stops mattering.