How Big Is a Cup, Really? American vs International Cup Sizes

Recipes from different countries use different cup sizes. The "cup" you grew up with is not universal — and the differences are big enough to ruin a recipe if you're not paying attention. Here's the world tour.

The four most common cup sizes

The U.S. cup (240 ml)

The standard American cup. Used in U.S. measuring cups, recipe books, and most international recipes that mention cups. Defined as 240 ml or 8 fluid ounces (U.S.).

Almost all U.S. cookbooks use this. Modern recipe sites (Allrecipes, Epicurious, NYT Cooking, Bon Appétit) all assume 240 ml when they say "1 cup."

The Australian cup (250 ml)

Australia and New Zealand use a 250 ml cup as their standard. The 4% difference matters in baking — an Australian cup of flour is 130 g vs 120 g for U.S.

If you're using an Australian recipe and U.S. measuring cups, you'll under-measure by about 4%. For most recipes that's invisible, but for sensitive baking it can matter.

The Imperial (UK) cup (284 ml)

Historical British cup, equal to half an Imperial pint (568 ml ÷ 2). Almost never used in modern UK recipes — most British cookbooks switched to grams in the 1970s. You may encounter it in old (pre-1970) British cookbooks.

If you see "1 cup" in a modern UK recipe, check the source — it may be using the U.S. 240 ml cup as a translation.

The Japanese cup (200 ml)

Japanese rice cookers use a 200 ml cup as the standard rice measurement. So do Japanese recipe books.

If you're cooking Japanese rice and using the cup that came with your rice cooker, you're using the Japanese 200 ml cup. The water-to-rice ratio is calibrated for this. Substituting a U.S. measuring cup throws off the ratio.

How much do these differences actually matter?

For cooking (soups, stews, sautés): not much. A 4% difference in stock is invisible in the finished dish.

For baking: matters more. A cup of flour is 120–130 g depending on which cup. A 4-cup recipe drifts 40 g — enough to change cake texture noticeably.

For very sensitive baking (puff pastry, croissants, soufflés): use weight (grams) instead. Cups of any flavor are not precise enough.

Other unit confusions

Tablespoons: mostly standard at 15 ml worldwide. The U.S. tablespoon is 14.79 ml, the metric one is 15 ml. Australia uses 20 ml — different from everywhere else!

Teaspoons: 5 ml worldwide.

Fluid ounces: the U.S. fl oz is 29.57 ml; the U.K. (Imperial) fl oz is 28.41 ml. The U.K. version is rare in modern recipes.

Ounces (weight): the same everywhere — 28.35 g.

Pints: U.S. pint is 473 ml. UK Imperial pint is 568 ml. Big difference.

How to identify which cup a recipe uses

1. Source country usually tells you. American cookbook → 240 ml. Australian cookbook → 250 ml. Japanese rice cooker manual → 200 ml.
2. Look for grams alongside cups. If a recipe says "1 cup (240 ml) flour" — confirmed U.S. If it says "1 cup (250 ml)" — Australian.
3. Look for related units. If the recipe uses "Imperial pint" or specifies "454 g = 1 lb," it's using British.
4. When in doubt, use the U.S. cup. 90% of online recipes you'll encounter assume the U.S. 240 ml cup, even if the writer is in Europe.

Australian tablespoons are weird

Australia is the only country whose tablespoon is 20 ml instead of 15. So an Australian recipe with "3 tablespoons" of butter equals 4 U.S. tablespoons.

This is the most common conversion error when working with Australian recipes. Look for it.

Going metric: the cleanest fix

If you're tired of cup math, switch to weight. Most modern recipes either include grams or are easy to convert with our cup-to-gram tool.

Once you're cooking by weight, the source country doesn't matter. 350 g of flour is 350 g of flour anywhere on Earth.

Convert quickly

Our cup-to-gram converter uses the U.S. 240 ml cup standard for ingredient weights. For Australian recipes, multiply the gram result by 1.04. For Japanese rice, the smaller cup means smaller portion sizes — adjust accordingly.