US Cup vs Metric Cup vs Imperial Cup: Which One Does Your Recipe Use?

5 min read · Updated October 20, 2026 · By Mohammad Dawood Edris Ghanizada

The word "cup" sounds like a fixed measure, but it is not. Different countries define it differently, and a recipe written in one country can quietly produce a different result in another. Understanding the main cup sizes helps you convert recipes accurately.

The main cup sizes

• US customary cup: 236.6 mL (8 US fluid ounces). Used in American recipes and by most conversion tools, including this site.
• US legal cup: 240 mL. Used on American nutrition labels.
• Metric cup: 250 mL. Used in Australia, New Zealand, South Africa and increasingly in Canada and the UK.
• Imperial cup: about 284 mL (half an imperial pint). Appears in older British recipes and is rarely used today.
• Japanese cup: 200 mL. Used for rice and in Japanese recipes.

How large is the difference?

The difference between a US cup (236.6 mL) and a metric cup (250 mL) is about 5.7 percent. In a recipe that needs 4 cups of flour, that adds up to roughly 3 tablespoons more flour. Often the recipe survives, but in sensitive bakes such as sponge cakes, macarons and bread it can matter.

Tablespoons and teaspoons differ too

A US tablespoon is about 14.8 mL, while an Australian tablespoon is 20 mL. A recipe asking for 3 Australian tablespoons of baking powder or salt would be far too strong if measured with US tablespoons by mistake, or the reverse. When a recipe uses spoons for leavening, salt or spices, check where it came from.

How to tell which cup a recipe uses

1. Look at the author's country, or the website's domain and spelling ("flavour" suggests UK, Australia or Canada).
2. Check whether grams are listed alongside cups. If so, trust the grams.
3. See whether the recipe uses "stick" of butter, "all-purpose" flour or Fahrenheit temperatures, which point to American origin.

Converting between cup systems

Multiply by 236.6 to turn US cups into millilitres, or by 250 to turn metric cups into millilitres. For dry ingredients, convert to grams first using the grams-per-cup value, then use the weight in your recipe. Our cups to millilitres converter handles liquids, and the cups to grams converter handles dry ingredients.

The safest approach

Whenever you can, convert to grams or millilitres and cook from those numbers. Weight and metric volume mean the same thing everywhere, which is exactly why they are the standard in professional kitchens and scientific work.