Cooking Measurement Conversions: Cups, Ounces, and Millilitres

Published 2026-10-01

Cooking conversions seem simple until a recipe from another country goes wrong. The problem is that “a cup” and “a fluid ounce” do not mean the same thing everywhere, and volume measures behave badly with dry ingredients like flour. This guide gives you the exact numbers, a small table you can trust, and the one habit that fixes most baking failures.

The three cups you might meet

There is no single international cup. The two you will actually encounter are:

• US cup: 236.5882365 ml exactly. This is the legal US cup, defined as half a US pint.
• Metric cup: 250 ml exactly. Used in Australia, New Zealand, Canada, and much of the rest of the world for recipes.

The difference is about 13 ml per cup, roughly 5.6 percent. For a soup, nobody notices. In a cake that calls for 4 cups of flour, the gap is over 50 ml, enough to change the texture.

Older British recipes may also use an informal imperial cup of 284 ml (half an imperial pint), but modern UK recipes almost always use the 250 ml metric cup or grams directly.

Fluid ounces: smaller in the UK

Fluid ounces are even trickier because the US and imperial versions differ in the opposite direction from what most people expect:

• US fluid ounce: 29.5735295625 ml.
• Imperial fluid ounce: 28.4130625 ml.

The imperial fluid ounce is smaller, but the imperial pint has 20 of them while the US pint has 16, so the imperial pint (568 ml) is bigger than the US pint (473 ml). If a British recipe says “half a pint of stock,” that is about 284 ml, not the 237 ml an American cook would pour.

You can check the US numbers against the cup: 8 US fluid ounces times 29.5735295625 ml equals 236.5882365 ml, exactly one US cup. The system is internally consistent; it just does not match the British one.

A quick conversion table

Worked example: a US recipe calls for 2 cups of milk. That is 2 times 236.5882365 ml, which is 473.176473 ml, so about 473 ml. If you are measuring with a metric jug, 475 ml is close enough, but do not pour 500 ml (two metric cups) into a delicate custard and expect identical results.

Going the other way: a metric recipe calls for 250 ml of cream. Dividing 250 by 236.5882365 gives about 1.057 US cups, so slightly more than one US cup.

Weight vs volume: the flour problem

Volume is a bad way to measure flour because flour compresses. A cup of flour scooped straight from the bag can weigh 30 percent more than a cup of flour that was spooned in lightly and levelled. That is the single biggest reason home bakers get dry, dense results from good recipes.

As a rough reference, one US cup of all-purpose flour weighs about 120 to 125 grams depending on how it was measured. Professional recipes avoid the ambiguity entirely by listing flour in grams. If your recipe only gives cups, use the spoon-and-level method: fluff the flour, spoon it into the cup, and level it off with a straight edge. Never pack it down.

Liquids are the opposite story. Water, milk, and oil do not compress, so volume measures are reliable for them, and one millilitre of water conveniently weighs one gram.

Practical takeaways

1. Check where the recipe is from. American cups are 236.59 ml; metric cups are 250 ml.
2. Remember that imperial fluid ounces (28.41 ml) are smaller than US ones (29.57 ml), but imperial pints are bigger.
3. Weigh flour and other dry ingredients in grams whenever you can.
4. When precision matters, convert to millilitres and measure once instead of converting cup by cup.

For instant conversions between cups, ounces, millilitres, and grams, use the volume and weight converters on our homepage. And if your recipe also lists oven temperatures in a scale you do not use, our temperature conversion guide covers those formulas too.