Quick answer: A US cup is 236.6 ml (8 US fl oz), while the metric cup used in Australia, New Zealand and Canada is 250 ml. The UK has no official cup measure: British recipes use grams and millilitres. US nutrition labels round the cup to 240 ml. If a recipe comes from an American site, assume 236.6 ml.
Cup measures cause more baking failures in British kitchens than almost any other conversion, because the word “cup” covers several different volumes. This guide sets them side by side, gives a converter and a fraction chart, and explains why weighing beats scooping. It belongs to our wider guide to how the UK measurement system works day to day.
Is there such a thing as a UK cup?
No, there is no legally defined UK cup. Modern British recipes are written in grams, millilitres and spoons, with ounces and fluid ounces sometimes given as well. When a UK writer does say “cup”, they normally mean either a US cup (because the recipe was adapted from an American source) or a rough everyday mug or teacup.
Older British cookery used household cups such as the teacup and the breakfast cup. One widely quoted 1960s description put the breakfast cup at about 8 imperial fluid ounces (227 ml) and the teacup at about 5 fluid ounces (142 ml), but these were typical sizes of crockery, not standard units. If an old family recipe calls for “a cup”, treat it as approximate.
| Cup measure | Millilitres | Fluid ounces | Where you will see it |
|---|---|---|---|
| US customary cup | 236.6 ml | 8 US fl oz (8.33 UK fl oz) | American recipes and cookbooks |
| US legal (labelling) cup | 240 ml | 8.12 US fl oz | US nutrition labels |
| Metric cup | 250 ml | 8.80 UK fl oz | Australia, New Zealand, Canada; many measuring-cup sets |
| Traditional Canadian cup | 227.3 ml | 8 UK fl oz | Older Canadian recipes |
| Japanese cup | 200 ml | 7.04 UK fl oz | Japanese recipes |
How many ml is a US cup compared with a metric cup?
A US cup is 236.59 ml and a metric cup is 250 ml, so the metric cup is about 13.4 ml (5.7%) bigger. For a single cup of milk the difference hardly matters. Over three or four cups of flour it adds up to a noticeably drier dough or a stiffer batter.
The US cup is defined as half a US pint, so it follows the American pint rather than the British one. A UK pint of 568 ml holds 2.4 US cups, not two; our explainer on the UK vs US pint difference shows why the two pints part company.
Cups to millilitres converter
Cups to ml (three cup standards)
cups= ml (US cup) · ml (US label cup) · ml (metric cup)The formula is simple: millilitres = cups × 236.588 for US recipes, or cups × 250 for Australian and New Zealand recipes. To go the other way, divide millilitres by the same figure. As a worked example, ¾ US cup of buttermilk is 0.75 × 236.588 = 177 ml, which you can measure in an ordinary British measuring jug.
US and metric cup conversion chart
| Cups | US cup (ml) | Metric cup (ml) | US label cup (ml) | US cup in UK fl oz |
|---|---|---|---|---|
| ¼ | 59.1 | 62.5 | 60 | 2.08 |
| ⅓ | 78.9 | 83.3 | 80 | 2.78 |
| ½ | 118.3 | 125 | 120 | 4.16 |
| ⅔ | 157.7 | 166.7 | 160 | 5.55 |
| ¾ | 177.4 | 187.5 | 180 | 6.25 |
| 1 | 236.6 | 250 | 240 | 8.33 |
| 1½ | 354.9 | 375 | 360 | 12.49 |
| 2 | 473.2 | 500 | 480 | 16.65 |
| 3 | 709.8 | 750 | 720 | 24.98 |
| 4 | 946.4 | 1,000 | 960 | 33.31 |
Why should you weigh dry ingredients instead of using cups?
A cup measures volume, so the weight you get depends on how tightly the ingredient is packed. Flour scooped straight from the bag can weigh noticeably more than flour spooned lightly into the cup. Kitchen scales remove that guesswork, which is why British recipes give grams.
King Arthur Baking, an American flour miller, publishes an ingredient weight chart that many bakers use as a reference. Its figures for one US cup include:
| Ingredient (1 US cup) | Grams | Ounces (approx.) |
|---|---|---|
| Plain (all-purpose) flour | 120 g | 4¼ oz |
| Granulated sugar | 198 g | 7 oz |
| Soft brown sugar, packed | 213 g | 7½ oz |
| Icing (confectioners’) sugar | 113 g | 4 oz |
| Butter (two US sticks) | 226 g | 8 oz |
Treat these as starting points rather than exact values, since flours and sugars vary. If you have no scales at all, our guide to measuring 100 g of flour without scales explains the spoon method, and the cooking converter handles grams, ounces and spoons.
Are UK and US spoons the same size?
Nearly: a UK tablespoon is 15 ml and a US tablespoon is 14.79 ml. The US teaspoon is 4.93 ml against the UK’s 5 ml. These gaps are too small to matter in normal cooking. The spoon to watch is the Australian tablespoon, which is 20 ml, so an Australian recipe’s “1 tbsp” is a third larger than a British one.
Common mistakes with cup recipes
- Using a mug. Mugs are not made to any standard size, so a “cup” of flour scooped with one can be well over or under the intended amount.
- Assuming a cup is half a UK pint. Half a UK pint is 284 ml, about 20% more than a US cup.
- Mixing systems in one recipe. If you convert the flour to grams, convert the liquids and sugar too, so the ratios stay intact.
- Ignoring the recipe’s origin. Australian and New Zealand recipes use 250 ml cups and 20 ml tablespoons; American ones use 236.6 ml cups.
Frequently asked questions
How many ml is 1 cup in the UK?
The UK has no official cup. Most recipes that mention cups mean the US cup of 236.6 ml, while measuring-cup sets are often marked as 250 ml metric cups. Check the ml marking on your cup.
Is a US cup 240 ml or 237 ml?
Both figures exist. The US customary cup used in recipes is 236.6 ml. The US Food and Drug Administration uses a rounded 240 ml cup for nutrition labelling.
How many US cups are in a UK pint?
A UK pint of 568 ml holds 2.4 US cups or 2.27 metric cups. A US pint holds exactly 2 US cups.
How many grams of flour are in a cup?
King Arthur Baking gives 120 g for one US cup of all-purpose flour. The real weight varies with how the cup is filled, so weighing is more reliable.
Can I use Australian cup recipes with a US cup set?
For most recipes, yes, because the cups differ by only 5.7%. Use the same cup for every ingredient to keep the ratios right, and remember Australian tablespoons are 20 ml.
Sources
- US FDA: guidelines for determining metric equivalents of household measures (240 ml labelling cup).
- NIST: unit conversion (US customary cup, pint and fluid ounce).
- King Arthur Baking: ingredient weight chart.
- Weights and Measures Act 1985 (definition of the UK pint and gallon).