Why use this calculator
A recipe never tells you which cup it means, and the four cups in circulation differ by up to twenty per cent. An American blogger writes in 236.588 mL cups, an Australian magazine writes in 250 mL cups, a British book from before metrication writes in 284.131 mL cups, and a nutrition panel uses the 240 mL legal cup.
Using the wrong one changes the liquid in a batter, the flour in a dough and the ratio between them at the same time, which is why a cake that works in one country collapses in another. This converter turns any cup figure into millilitres first, then back into the cup you actually own, and shows the size gap as a percentage so you can judge whether it matters for the dish in front of you.
How to use it
- Enter the number of cups the recipe asks for in the amount box, using decimals such as 0.5 for half a cup or 0.75 for three quarters.
- In the second field choose the cup the recipe was written with, taking the country of publication as your guide, so a US site means the customary cup, an Australian or New Zealand source means the 250 mL metric cup, and an older British book means the imperial cup.
- In the third field choose the cup you are holding, which for anyone measuring with a metric set is the 250 mL cup.
- Read the highlighted converted amount, then check the millilitre row if you would rather pour into a measuring jug and skip cups altogether.
What each result means
- Converted amount
- How many of your cups hold the same volume the recipe asked for. This is the number to measure by.
- Volume in millilitres
- The true volume behind the recipe figure. Pouring this into a jug removes every cup standard from the question.
- In US customary cups (236.6 mL)
- The same volume counted in the American kitchen cup, which is half a US liquid pint.
- In US legal cups (240 mL)
- The same volume in the cup used on US nutrition labels, defined by regulation as exactly 240 millilitres.
- In metric cups (250 mL)
- The same volume in the Australian and New Zealand cup, which is also the standard metric cup in Europe.
- In UK imperial cups (284.1 mL)
- The same volume in the old British cup, which is half an imperial pint and the largest of the four.
- In metric tablespoons (15 mL)
- Useful for small amounts, where counting spoons is more accurate than part filling a cup.
- Size gap between the two cups
- How much larger or smaller the recipe's cup is than yours, and the millilitre error you would make by ignoring it.
The formula
The conversion is a two step volume change:
- Volume_mL = amount x fromCup_mL
- Then result = volume_mL / toCup_mL
Here amount is the number of cups in the recipe, fromCup_mL is the millilitre capacity of the recipe author's cup, and toCup_mL is the capacity of your cup. The capacities are fixed constants: US customary 236.588 mL, US legal 240 mL, metric 250 mL and UK imperial 284.131 mL. The size gap shown underneath is (fromCup_mL - toCup_mL) / toCup_mL x 100, expressed as a percentage.
How this number is used in practice
The failure people describe as a bad recipe is usually a cup mismatch. Take an American cake that calls for two cups of flour and one cup of milk. Measured with an Australian 250 mL cup set, the cook adds about 27 mL more flour and 13 mL more milk than intended, but the flour is a compressible powder and the milk is not, so the hydration of the batter drops.
The result is a drier, tighter crumb that browns faster, and nothing in the recipe explains why. Going the other way, an Australian scone recipe made with American cups comes out wet and spreads flat.
The gap matters most where a ratio is doing the work. Bread, pastry, custards and anything set with gelatine or eggs depend on proportions rather than absolute quantities, so a five per cent shift in one ingredient shows up immediately. A pot of soup or a tray of roast vegetables will not care.
This is why published recipes increasingly give weights in grams next to the cups, and why serious bakers keep a digital scale on the bench: a gram is a gram in every country, while a cup is four different volumes wearing the same name.
Worked examples
An American recipe asking for 2 cups, measured with an Australian metric cup
1.893 metric cups, or 473.2 mL
One UK imperial cup from an older British book, in US customary cups
1.201 US customary cups, or 284.1 mL
500 mL of stock expressed in metric cups
2.000 metric cups
When people use it
- Cooking an American recipe with an Australian or New Zealand measuring cup set
- Rewriting a family recipe from an old British cookbook into metric volumes
- Checking a nutrition label serving size against the cup you measure with
- Scaling an international recipe up or down without compounding a cup error
- Deciding when a cup difference is small enough to ignore and when it is not
Tips
- Convert to millilitres once and pour from a jug: it removes every cup standard from the recipe in one step.
- A US customary cup is about 5.4 per cent smaller than a metric cup, so four American cups are only about 3.8 metric cups.
- The UK imperial cup at 284.131 mL appears in books published before metrication. Modern British recipes use the 250 mL metric cup.
- Nutrition panels in the United States use the 240 mL legal cup, which is not the same as the cup in an American measuring set.
- Fill liquid cups on a level bench and read at eye level. Holding the cup up tilts the meniscus and costs several millilitres.
- For dry ingredients, weigh instead of converting. Grams do not change between countries and remove the packing question entirely.
What it assumes, and where it stops being accurate
- Cup capacities are the published standards of 236.588 mL, 240 mL, 250 mL and 284.131 mL. Cheap measuring cups vary by a few millilitres.
- The conversion is pure volume. It says nothing about weight, which depends on the ingredient and how tightly it is packed.
- The recipe author actually used their national standard, which is not guaranteed on unsourced recipe sites.
- Liquid and dry cups of the same nominal size hold the same volume. The difference between the two is how you fill and read them.
- Results are rounded for display, so converting back and forth repeatedly can drift by a millilitre.
Terms used on this page
- US customary cup
- Half a US liquid pint, 236.588 mL. The cup an American measuring set is made to.
- US legal cup
- Exactly 240 mL, defined in US food labelling regulation for nutrition panel serving sizes.
- Metric cup
- Exactly 250 mL, the standard cup in Australia, New Zealand and most metric recipe writing.
- Imperial cup
- Half an imperial pint, 284.131 mL. Found in British cookbooks published before metrication.
- Meniscus
- The curved surface of a liquid in a measure. Read the bottom of the curve at eye level.
Questions people ask
- How many millilitres are in a cup?
- It depends which cup. The US customary cup is 236.588 mL, the US legal cup used for nutrition labelling is exactly 240 mL, the metric cup used across Australia and New Zealand is 250 mL, and the older UK imperial cup is 284.131 mL, which is half an imperial pint. Always check where the recipe was published before assuming.
- Are Australian and metric cups the same?
- Yes. Australia and New Zealand adopted the 250 mL metric cup, so an Australian recipe and a European metric recipe use an identical measure. The one to watch is the US customary cup at 236.588 mL, which is about 5.4 per cent smaller and enough to change the texture of a baked item.
- Why do cup sizes differ between countries?
- They grew out of different measurement systems. The US customary cup descends from the US liquid pint, the UK cup from the larger imperial pint, and the metric cup was defined as a round 250 mL when Australia and New Zealand converted to metric units. None of them was designed to match the others, and no international body ever reconciled them.
- Does the difference actually matter in baking?
- In anything ratio driven, yes. Bread, pastry, sponge cakes and custards depend on the proportion of flour to liquid to fat, so a five per cent shift in one of them changes the result. Soups, stews and roast vegetables are forgiving enough that the same shift will pass unnoticed.
- What is the difference between a US customary cup and a US legal cup?
- The customary cup of 236.588 mL is what American measuring cups are made to and what recipes mean. The legal cup of exactly 240 mL is defined in food labelling regulation and appears in nutrition panel serving sizes. The gap is about 1.4 per cent, which matters for label comparisons rather than for cooking.
- Should I convert cups or just weigh everything?
- Weigh where you can. A gram means the same thing in every country, whereas a cup of flour can vary by twenty per cent depending on the cup standard and how the flour was scooped. Use cup conversion for liquids and for recipes that give only volumes, and use a scale for flour, sugar and anything structural.
Use this with
Cup Converter answers one part of the question. These pick up where it stops: Cups to Grams Converter, Tablespoon and Teaspoon Converter, Recipe Scaler and Oven Temperature Converter.
Where these figures come from
This calculation is jurisdiction-neutral arithmetic. No country-specific rules are applied.
- NIST Office of Weights and Measures. US customary volume definitions and Handbook 44
- US FDA food labelling and nutrition. Defines the labelling cup as 240 mL, tablespoon 15 mL, teaspoon 5 mL
- Food Standards Australia New Zealand. Australian and New Zealand metric measures and food safety guidance
Cup Converter produces an estimate for general information. It is not financial, tax, medical, legal or engineering advice. read the full disclaimer. Spotted a wrong number? Report it and it gets fixed. The form picks up this calculator and the inputs you used.