US Cups vs Metric Cups: What Home Cooks Need to Know
The difference between US cups (236.6 mL), the 240 mL cup on US nutrition labels, and metric cups (250 mL), plus the tablespoon trap in Australian recipes.
Three Different "Cups"
A recipe that says "1 cup" can mean slightly different amounts depending on where it was written. There are three you're likely to meet:
- US cup: about 236.6 mL (8 US fluid ounces). This is what American recipes mean.
- US "legal" cup: exactly 240 mL. The FDA uses this rounded cup for serving sizes on nutrition labels. You won't usually see it in recipes.
- Metric cup: exactly 250 mL. Used in Australia and New Zealand, and commonly in Canada and South Africa.
What About British Recipes?
Modern British recipes mostly skip cups and give weights in grams and liquids in milliliters, which avoids the problem altogether. Older British recipes sometimes used an imperial cup of about 284 mL (half an imperial pint), but you'll rarely see that today.
If a British recipe does say "cup" and gives no metric amounts, it was most likely written for an international audience using the 250 mL metric cup.
Does the Difference Actually Matter?
The gap between a US cup and a metric cup is 13.4 mL, about 6%. In soups, stews, sauces, and stir-fries you will never notice. You're adjusting to taste anyway.
In baking it can show up, because every cup in the recipe is off by the same 6%. If all the ingredients use the same cup, the proportions stay the same and the recipe just makes about 6% more or less. Problems appear when you mix systems: measuring the flour with a metric cup but the milk with a US cup, for example. Then the batter can end up slightly wetter or drier than intended.
The Tablespoon Trap
Teaspoons are nearly identical everywhere: 5 mL metric, 4.93 mL US. Tablespoons are not. In the US, UK, Canada, and New Zealand, a tablespoon holds about 15 mL (3 teaspoons). In Australia, the standard tablespoon is 20 mL (4 teaspoons).
That difference is a third. For flavorings it hardly matters, but for baking powder, baking soda, salt, or yeast it can. If you use an Australian tablespoon for an American recipe, you'll add a third more leavening than intended. The reverse is true for an Australian recipe made with US spoons.
- Australian recipe, US spoons: for each tablespoon, use 1 US tablespoon plus 1 teaspoon.
- US recipe, Australian spoons: for each tablespoon, use 3 teaspoons instead of the Australian tablespoon.
Quick Conversions
These are the most useful numbers to keep on hand:
- 1 US cup = 236.6 mL = 16 tablespoons = 48 teaspoons = 8 US fl oz
- 1 metric cup = 250 mL, about 1.06 US cups
- 1/2 US cup = 118 mL; 1/3 US cup = 79 mL; 1/4 US cup = 59 mL
- 1 US fluid ounce = 29.6 mL
- 1 US pint = 2 cups = 473 mL; 1 US quart = 4 cups = 946 mL
Common questions
How many mL is a cup in Australia?
250 mL. Australian and New Zealand recipes use the metric cup.
Why does a nutrition label say a cup is 240 mL?
FDA labeling rules use a rounded 240 mL cup for serving sizes. It's close to the 236.6 mL US cup used in recipes, but not exactly the same.