A US customary cup holds about 237 milliliters (236.588 ml to be exact). But “cup” is not one single amount worldwide. The US legal cup, used on nutrition labels, is rounded to 240 ml, and the metric cup used in Australia, New Zealand, and much of Europe is 250 ml. That means a “cup” can vary by more than 5 percent depending on where the recipe was written, which is enough to matter in baking.
The three (and a half) cups
Here is every common definition of a cup side by side:
| Type of cup | Milliliters | Where it is used |
|---|---|---|
| US customary cup | 236.588 ml (~237 ml) | Most US recipes and measuring cups |
| US legal cup | 240 ml | US nutrition labels and FDA rules |
| Metric cup | 250 ml | Australia, New Zealand, Canada, much of Europe |
| Imperial (UK) cup | ~284 ml | Older British recipes (rarely used today) |
Which cup does your recipe mean?
For everyday US cooking, assume the customary cup of about 237 ml. Rounding it to 240 ml, the legal cup, introduces only a 1.4 percent difference, so the two are interchangeable for most dishes. The one to watch is the 250 ml metric cup: if your recipe comes from Australia, New Zealand, or a European source, each “cup” is about 5 percent larger than a US cup, and that gap compounds when a recipe uses several cups of flour or liquid. Modern British recipes usually give metric weights instead, but very old ones may assume the larger imperial cup near 284 ml.
Common US cup fractions in milliliters
Working from the US customary cup, here are the fractions you will use most:
| US cup fraction | Milliliters (approx.) | Fluid ounces |
|---|---|---|
| 1 cup | 237 ml | 8 fl oz |
| 3/4 cup | 177 ml | 6 fl oz |
| 1/2 cup | 118 ml | 4 fl oz |
| 1/3 cup | 79 ml | 2.67 fl oz |
| 1/4 cup | 59 ml | 2 fl oz |
Milliliters are the universal language
Because “cup” is ambiguous, milliliters are the safest way to record and share a recipe. A milliliter means the same volume in every country, so when you convert cups to milliliters up front, you remove any doubt about whose cup was intended. If you own a metric measuring jug marked in milliliters, you can follow US and international recipes alike simply by using the correct milliliter figure. This is why many cooks who bake across cuisines quietly switch to milliliters and grams and never look back.
It also future-proofs your own notes. If you jot down a family recipe in “cups,” a relative in another country may reproduce it with a different-sized cup and get a different result. Writing it in milliliters, or better still weighing the dry parts in grams, means the recipe travels intact. For liquids where a small variance will not matter, such as a soup or a braise, the difference between cup definitions is harmless; it is precise baking, where ratios drive the outcome, that rewards the extra care.
How this connects to ounces and tablespoons
The US cup ties neatly to the other units: 237 ml is 8 US fluid ounces, and each fluid ounce is about 29.57 ml. It is also 16 tablespoons, so each US tablespoon is about 14.79 ml, and 48 teaspoons at roughly 4.93 ml each. If you want those relationships spelled out, see our guides to how many ounces are in a cup and how many tablespoons are in a cup. For weight-based conversions on dry goods, our note on how many grams are in an ounce covers the scale side.
A worked international example
Suppose you find an Australian cake recipe that calls for 2 cups of milk, and you only have US measuring cups. The Australian cup is the 250 ml metric cup, so 2 cups is 500 ml. Measured with your US cup at about 237 ml, 2 cups would give only 474 ml, about 26 ml short, roughly 2 tablespoons less milk than the recipe intended. For a forgiving dish that gap is minor, but for a delicate batter it can change the texture. The fix is simple: convert the recipe’s cups to milliliters first, then measure that milliliter amount, and the origin of the cup no longer matters.
A note on dry vs. liquid cups
Whether you are measuring a liquid or a dry ingredient, a cup is the same volume, 237 ml for the US customary cup. The difference is in the tool: liquid measuring cups have a spout and headroom so you can fill to a line without spilling, while dry measuring cups are meant to be filled and leveled off flat. Using the right style makes your milliliter conversion actually land where it should.
The bottom line
A US cup is about 237 ml, the US legal cup is 240 ml, and the metric cup is 250 ml, so always check which system your recipe uses. When in doubt, convert everything to milliliters or grams, the two measures that mean the same thing no matter where the recipe came from. A cheap measuring jug marked in milliliters is all you really need to cook confidently from recipes written anywhere in the world.
