mL to Cups Converter

Article — mL to Cups Converter

mL to cups: the five definitions of "1 cup" and how to tell which one you need

A US customary cup is 236.59 millilitres. The US legal cup, used on FDA nutrition labels, is 240 mL. The metric cup, standard in Australia, New Zealand, Canada, and modern European recipes, is 250 mL. The British imperial cup is 284 mL. The Japanese cup is 200 mL. Same word, five different volumes - a 42% spread from smallest to largest. The calculator above runs the conversion in both directions for all five.

For most American recipes, leave the dropdown on US customary and the result will match what cookbook authors expect. For Australian, New Zealand, or modern European recipes, switch to the metric cup (250 mL) - the math is cleaner because 1 litre is exactly 4 metric cups.

How many millilitres are in a cup?

The answer depends entirely on which cup the recipe is referencing. The same number on the side of a coffee mug can mean four different things depending on where the mug was manufactured and which authority set the standard.

• Japanese cup = 200 mL (traditional sho rice scale)
• US customary cup = 236.59 mL (US recipes, the default for most American cookbooks)
• US legal cup = 240 mL (FDA nutrition labels, 21 CFR 101.12)
• Metric cup = 250 mL (Australia, New Zealand, Canada, modern Europe)
• Imperial UK cup = 284 mL (older British recipes pre-1971)

NIST's Metric Kitchen reference and the USDA's measurement conversion tables both use the US customary cup (236.59 mL) when converting between mL and cups for recipes. The FDA's Nutrition Facts panel uses the 240 mL legal cup. Both are correct in their own contexts, which is what makes the whole topic confusing in the first place.

The five cup standards in use today

Each of the five values has a documented origin. None of them is wrong - they are just different. Modern recipes and food regulations specify which they mean. Older recipes often do not, which is the most common source of conversion errors in kitchens.

US customary versus metric - the 5.4% gap

The US customary cup of 236.59 mL is what's used in cookbooks published in the United States. The metric cup of 250 mL is what's used almost everywhere else in the English-speaking world, plus most of Europe. The two values differ by 13.41 mL, or 5.4%. For a single cup that is barely noticeable; for a recipe calling for four or five cups it adds up to a meaningful difference.

4 US cups equals 946.35 mL. 4 metric cups equals exactly 1000 mL - 1 litre. That difference of 53.65 mL across a four-cup recipe is enough to change the texture of bread dough, the doneness of custards, and the boiling time of soups. Professional translators of cookbooks routinely re-test recipes when converting between US and metric editions for this reason.

Why the FDA chose 240 mL

In 1973 the FDA needed a standardised cup for nutrition labelling. The US customary cup (236.59 mL) was the obvious choice, but the value is awkward to print on a label. The FDA chose to round it up to 240 mL - a cleaner number, mathematically convenient because it gives exactly 8 servings of 30 mL per cup. The rounded value was formalised in 21 CFR 101.12 ("Reference Amounts Customarily Consumed") and remains the legal definition for US nutrition labelling under the Nutrition Labeling and Education Act of 1990.

Common 100, 250, 500 and 1000 mL conversions

The most-searched volumes and their cup equivalents across the four major standards:

The 1832 US Treasury decision that fixed the cup

The US customary cup is a chain of inherited definitions going back to 18th-century England. In 1707, Queen Anne signed legislation fixing the British wine gallon at exactly 231 cubic inches - a value already in customary use among London wine merchants. When the United States gained independence, the new country kept the wine gallon as its standard.

In 1832, the US Department of the Treasury formally restated the gallon at 231 cubic inches for federal use. Britain, in 1824, had moved on to a new imperial gallon of 277.42 cubic inches - which is why US and UK gallons (and therefore cups, pints, and quarts) are different sizes to this day. The US cup, at 1/16 of the US gallon, settled at 14.4375 cubic inches, which converts to 236.5882365 mL. That awkward fractional value is the price the US pays for keeping a definition that predates the metric system by almost a century.

Cooking, baking, and when to switch to grams

For soups, stews, sauces, and one-pot dishes, the difference between cup standards rarely matters - the recipe is forgiving enough that 240 mL versus 250 mL changes nothing. For baking, the gap matters: a bread recipe that needs 60% hydration by weight is sensitive to the exact mL of water added per gram of flour. Professional bakeries do not use cups at all; they weigh everything in grams.

Which cup does your country use?

If you are following an American recipe, leave the calculator on US customary (236.59 mL). If you are following an Australian, New Zealand, or Canadian recipe, switch to metric (250 mL). For older British recipes - generally anything published before the UK metric transition of the 1970s - use the imperial cup (284 mL). For Japanese cooking, especially traditional rice recipes, use the Japanese cup (200 mL). For anything found on a Nutrition Facts panel, use the FDA legal cup (240 mL). The five definitions cover almost every recipe context you will encounter.