US Cup vs Metric Cup vs UK Cup: What Is the Difference?
You found a great recipe online. It says "1 cup of milk." Simple, right? Not quite. Depending on where the recipe was written, a "cup" can mean three different amounts.
For most dishes the difference is small. For baking, it can be the reason a cake rises perfectly or sinks in the middle.
The three cups at a glance
| Cup type | Milliliters | Used in |
|---|---|---|
| US customary cup | 236.6 ml | United States |
| Metric cup | 250 ml | Australia, Canada, New Zealand, South Africa, and many modern UK recipes |
| Imperial (old UK) cup | 284 ml | Older British recipes |
There is also the US legal cup (240 ml) used on nutrition labels in the United States. It is close enough to the customary cup that you can treat them the same in the kitchen.
How big is the difference?
A metric cup holds about 6% more than a US cup. That is roughly one extra tablespoon per cup.
- In a soup, stew or curry, you will never notice.
- In a cake that uses 3 cups of flour and 2 cups of sugar, it adds up to several extra tablespoons, which can change the texture.
The old imperial cup is about 20% larger than a US cup, so if you are cooking from a vintage British cookbook, the difference is big enough to matter.
How to tell which cup a recipe uses
- Check where it is from. American websites and cookbooks almost always use the US cup.
- Look at other units. If the recipe also lists ounces, Fahrenheit, or sticks of butter, it is probably American.
- Metric hints. Recipes that list ml, grams and Celsius alongside cups usually mean the 250 ml metric cup.
- When in doubt, use grams. Weight is the same everywhere. 100 g of sugar is 100 g in every country.
Spoons are different too
Tablespoons also vary:
- US tablespoon: 14.8 ml
- UK and most metric tablespoons: 15 ml
- Australian tablespoon: 20 ml
Teaspoons are nearly universal at about 5 ml.
Our converters use the US cup
Every result on GramsInCup uses the US customary cup of 236.6 ml, because that is what most online recipes are written in. If you need to convert milliliters, use our ml to cups converter or cups to ml converter.
Quick summary
- US cup = 236.6 ml, metric cup = 250 ml, old UK cup = 284 ml.
- The difference matters most in baking.
- If a recipe gives grams, use them. Weight never changes from country to country.