US cup vs metric cup vs UK cup: differences
Quick answer: a US cup is 236.6 ml, a metric cup is 250 ml, and the UK does not normally use cups at all. The gap between a US and metric cup is about 5.7 percent, which matters in baking.
The units side by side
| Measure | US customary | Metric | UK imperial |
|---|---|---|---|
| Cup | 236.6 ml | 250 ml | not standard |
| Tablespoon | 14.8 ml | 15 ml | 15 ml (17.7 ml in the old imperial system) |
| Teaspoon | 4.9 ml | 5 ml | 5 ml |
| Fluid ounce | 29.57 ml | not used | 28.41 ml |
| Pint | 473 ml (16 fl oz) | not used | 568 ml (20 fl oz) |
| Gallon | 3.785 liters | not used | about 4.55 liters |
The Australian tablespoon is a special case: it is 20 ml, which equals 4 teaspoons. See how many teaspoons are in a tablespoon.
Where each cup is used
- US cup: American recipes, and most US measuring cups.
- Metric cup (250 ml): Australia, New Zealand and many Canadian recipes that use metric.
- UK recipes: normally give weights in grams and volumes in milliliters. Old British recipes may use imperial pints and fluid ounces.
If a recipe does not say where it comes from, look at the other clues: ounces and Fahrenheit temperatures point to the US, while grams and milliliters point to a metric recipe.
Does the difference matter?
For a soup, sauce or stew, not really. For baking, it can. If a metric recipe calls for 2 cups of flour and you use US cups, you use about 5 to 6 percent less flour, which can leave a cake denser or wetter than intended. Batter and dough recipes are the most sensitive.
The best fix is to weigh ingredients if the recipe gives weights. If it only gives cups, use the cup size the recipe author assumed.
Converting between them
- 1 US cup = 236.6 ml
- 1 metric cup = 250 ml
- 1 metric cup = 1.057 US cups, so a metric cup is a little over a US cup
- To convert US cups to ml, multiply by 236.6. For metric cups, multiply by 250.
Our cups to milliliters converter uses the exact US value.
Frequently asked questions
Is a metric cup bigger than a US cup? Yes, by about 5.7 percent.
Can I use a US measuring cup for a metric recipe? For most cooking, yes. For precise baking, weigh the ingredients instead.
Why are US and UK pints different? The US customary system kept the older wine gallon measures, while the UK later adopted the imperial system in 1824.
For weights instead of volumes, see cups to grams: why there is no single answer.