Cup Sizes Around the World: US, Metric, Imperial & Japanese

The five cups

Cup — Millilitres — US fluid ounces — Used in

Japanese cup — 200 ml — 6.8 fl oz — Japanese recipes

US customary cup — 236.6 ml — 8.0 fl oz — American recipes

US legal cup — 240 ml — 8.1 fl oz — US nutrition labels

Metric cup — 250 ml — 8.5 fl oz — Australia, New Zealand, Canada

Imperial cup — 284.1 ml — 9.6 fl oz — Older British recipes

The US customary cup is the one nearly every recipe on the internet means, because so much recipe content is American. It is defined as half a US pint: 236.5882365 ml exactly.

Which cup does your recipe mean?

Go by origin, not by the word.

American blogs, American cookbooks, most global recipe sites — US customary, 236.6 ml.

Australian and New Zealand recipes — metric cup, 250 ml. Australia standardised this deliberately so a litre would be exactly four cups.

Canadian recipes — metric cup officially, though a lot of Canadian home cooking follows American measures in practice.

British recipes — usually grams and millilitres. Britain largely abandoned cups. Where an older book does use them, assume the imperial cup.

Japanese recipes — 200 ml. Separately, a rice cup (one gō) is 180 ml, and the plastic cup that comes with a rice cooker is that size.

How much the difference matters

Six percent between a US and a metric cup sounds trivial. Scale it up and it stops being trivial.

Recipe amount — In US cups — In metric cups — Difference

1 cup flour — 125 g — 132 g — 7 g

3 cups flour — 375 g — 396 g — 21 g

1 cup water — 237 ml — 250 ml — 13 ml

3 cups water — 710 ml — 750 ml — 40 ml

Twenty-one grams of flour in a cake is roughly an eighth of a cup — enough to firm up a crumb that was meant to be tender. Forty millilitres of water in a bread dough is a visible change in hydration.

The imperial cup is worse. At 284 ml it is 20% larger, so three imperial cups of flour is 450 g against 375 g for US cups. That is not a nudge, it is a different recipe.

Tablespoons diverge too

The cup is not the only unit that shifts.

Region — Tablespoon — Teaspoons in it

United States — 14.79 ml — 3

United Kingdom — 15 ml — 3

Metric / Europe — 15 ml — 3

Australia — 20 ml — 4

Australia's 20 ml tablespoon is the outlier, and it matters most for the ingredients measured in single spoonfuls. An Australian recipe calling for a tablespoon of baking powder wants a third more than an American one — enough to taste.

If you are cooking Australian recipes with US spoons, use one tablespoon plus one teaspoon wherever it says one tablespoon.

Pints and gallons, where it gets worse

The imperial system did not simply scale the American one — it went a different way.

Measure — US — Imperial

Fluid ounce — 29.57 ml — 28.41 ml

Fluid ounces per pint — 16 — 20

Pint — 473 ml — 568 ml

Quart — 946 ml — 1137 ml

Gallon — 3785 ml — 4546 ml

Note the reversal: the imperial fluid ounce is smaller, but there are more of them in a pint, so the imperial pint is larger by about 20%. A British recipe calling for a pint of cream wants nearly a fifth more than a US pint delivers.

The fix that ends the problem

Use grams.

Weight is the same everywhere. A gram is a gram in Sydney, Chicago and Osaka, and no amount of national tradition changes it. This is exactly why professional recipes and every serious modern cookbook are written in weight.

If a recipe gives both cups and grams, use the grams and ignore the cups entirely — the ambiguity vanishes.

If it gives only cups, work out which cup it means from where it was written, then convert. The cups to millilitres converter has all five cups in its unit list, and the universal kitchen converter will take it the rest of the way into grams for a specific ingredient.

A quick reference for converting between cup systems

US cup → metric cup: multiply by 0.946

Metric cup → US cup: multiply by 1.057

US cup → imperial cup: multiply by 0.833

Imperial cup → US cup: multiply by 1.2

Or, more simply: a recipe in metric cups needs about 6% more of everything if you measure it in US cups, and a recipe in imperial cups needs about 20% more.

For a full breakdown of what each amount weighs, the ingredient index lists grams per US cup for every ingredient on the site.

Frequently asked questions

How big is an Australian cup?

250 ml — the metric cup, also used in New Zealand and Canada. It is about 5.7% larger than a US cup.

Is a UK cup the same as a US cup?

Modern British recipes almost always use grams and millilitres rather than cups. Where an older British book does say cup, it usually means the imperial cup of 284 ml, which is 20% larger than a US cup.

Does the cup difference actually matter?

For soups, stews and anything forgiving, no. For cakes, bread and pastry, yes — a 6% change in flour or liquid is enough to alter the texture, and 20% will change the recipe entirely.

What is a US legal cup?

240 ml, used for nutrition labelling in the United States. It is a rounded version of the 236.6 ml customary cup and only appears on packaging, not in recipes.

How do I know which cup a recipe means?

Go by where it was written. American sites and books mean 236.6 ml; Australian and New Zealand ones mean 250 ml. If the recipe gives grams as well, use the grams and the question disappears.