A British baking blog, an American cookbook and an Australian recipe video can all say “1 cup” and mean three different volumes — and the tablespoon situation is worse. None of the gaps are huge alone; scaled up and compounded across a recipe, they're the difference between a batter and a paste.
The cups actually in circulation
| “Cup” | Volume | Where you'll meet it |
|---|---|---|
| US legal cup | 240 ml | US nutrition labels, modern US measuring cups, this site |
| US customary cup | 236.6 ml | older US cookbooks; the difference from 240 is noise (1.4%) |
| Metric cup | 250 ml | Australia, New Zealand, Canada, most translated recipes |
| Japanese cup | 200 ml | Japanese recipes and rice-cooker cups — the big outlier |
UK recipes mostly skip cups entirely: older ones use imperial pints (568 ml — bigger than the US pint's 473 ml) and weight in ounces; modern ones are sensibly metric in grams and millilitres.
Spoons disagree too
| Measure | US | UK / metric | Australia |
|---|---|---|---|
| Teaspoon | 5 ml | 5 ml | 5 ml |
| Tablespoon | 15 ml | 15 ml | 20 ml |
The Australian tablespoon is 4 teaspoons, not 3. An American making an Australian recipe under-measures every tablespoon line by 25% — invisible in olive oil, very visible in baking powder.
Which system is my recipe in? A field guide
- Fahrenheit oven temps, sticks of butter, “all-purpose flour” → US cups (240 ml).
- Grams and ml alongside cups, “caster sugar”, “plain flour” → metric cups (250 ml), likely AU/NZ — and remember their 20 ml tablespoon.
- Ounces and pints with no cups at all, gas marks → older UK; convert by weight, and note the bigger pint.
- “1 rice cup” → 180 ml, the traditional gō — rice cookers ship with that cup, and it is neither 200 nor 240 ml.
When the gap matters — and when it doesn't
US 240 vs metric 250 is about 4%. For vegetables, broth or pasta water, ignore it. It starts to matter where ratios are structural and amounts repeat: flour measured four cups deep compounds a 4% gap into most of an extra half-cup across a doubled batch, and leavening or salt mismatches track along with it. The tablespoon gap (33% in Australia's direction) always matters for anything potent.
The system-proof move is the same one that fixes most measuring problems: find or compute the weights once — grams care nothing for which empire defined your cup. Our conversion chart uses the US 240 ml cup throughout, which is also what the calculator assumes.
Skip the long division. Paste your ingredient list into the scaling pot and get every line converted at once.
Open the calculator