A cup is not the same everywhere
Kitchen cups and spoons look universal, but at least five different cups appear in recipes written in English or translated from other languages:
- US customary cup, 236.59 mL. Half a US pint, or 8 US fluid ounces, derived from the 231-cubic-inch US gallon. This is the cup in most American cookbooks and on American measuring sets.
- US legal cup, 240 mL. US federal rules for nutrition labels state that “a cup means 240 mL”, alongside a 15 mL tablespoon and 5 mL teaspoon (21 CFR 101.9). It applies to serving sizes on food packaging, not to measuring cups.
- Metric cup, 250 mL. The cup in Australian and New Zealand recipes and measuring sets. Canada’s food labelling rules also treat a cup as 250 mL and a tablespoon as 15 mL.
- Imperial cup, about 284 mL. Half an imperial pint, or 10 imperial fluid ounces; found mostly in older British recipes. The converter has no separate imperial cup, so enter 10 imperial fluid ounces to get it (284.13 mL).
- Japanese cup, 200 mL. The standard measuring cup in Japanese recipes.
Spoons differ too. A US tablespoon is 14.79 mL, the metric tablespoon used in the UK, Canada and New Zealand is 15 mL, and Australian recipes and measuring sets use a 20 mL tablespoon, which equals four 5 mL teaspoons instead of three. The US teaspoon is 4.93 mL and the metric teaspoon 5 mL.
Cup and spoon formulas
The US factors are exact fractions of the US gallon (1/16 for the cup, 1/256 for the tablespoon). The metric, legal and Japanese values are round numbers by definition.
Inside one system the ratios stay simple: 3 US teaspoons make a US tablespoon, 16 US tablespoons make a US cup, and a metric cup holds 12.5 Australian tablespoons or about 16.7 metric tablespoons.
Volume is not weight
The converter works in volume only. A US cup of water weighs about 236 g, but a cup of flour, sugar or rice is not a fixed number of grams. Flour spooned loosely into a cup weighs noticeably less than flour scooped and packed, sifting changes it again, and different brands and grinds settle differently. Any single “grams per cup” figure is therefore an average that may not match your bag or your technique, which is why this page does not offer a density table.
NIST’s culinary guidance calls weighing ingredients on a kitchen scale a best practice for accuracy, and says the safest way to convert an ingredient in a traditional American recipe is to measure it with the American cup or spoon, then weigh the result in grams. Liquids convert well by volume; dry goods are better weighed.
Worked examples
- One US cup is 236.5882365 mL.
- 2 × 236.5882365 = 473.18 mL, so measure 475 mL on a metric jug.
- An Australian tablespoon is 20 mL, so 2 tbsp = 40 mL.
- Divide by the US tablespoon: 40 ÷ 14.7868 = 2.705 US tbsp.
- In US teaspoons: 40 ÷ 4.9289 = 8.12, so 2 US tablespoons plus 2 teaspoons is close.
- 0.75 × 250 = 187.5 mL.
- 187.5 ÷ 236.5882365 = 0.7925 US cup, a little over ¾ US cup.
- 240 ÷ 236.5882365 = 1.0144.
- The difference is about 3.4 mL per cup, smaller than the error of filling a cup by eye.
Cooking measures table
| US customary cups (US cup) | Milliliters (mL) | Metric cups (metric cup) | US tablespoons (US tbsp) |
|---|---|---|---|
| 0.25 | 59.15 | 0.2366 | 4 |
| 0.5 | 118.3 | 0.4732 | 8 |
| 0.75 | 177.4 | 0.7098 | 12 |
| 1 | 236.6 | 0.9464 | 16 |
| 1.25 | 295.7 | 1.183 | 20 |
| 1.5 | 354.9 | 1.42 | 24 |
| 2 | 473.2 | 1.893 | 32 |
| 3 | 709.8 | 2.839 | 48 |
| 4 | 946.4 | 3.785 | 64 |
| Milliliters (mL) | US teaspoons (US tsp) | US tablespoons (US tbsp) | US customary cups (US cup) |
|---|---|---|---|
| 5 | 1.014 | 0.3381 | 0.02113 |
| 15 | 3.043 | 1.014 | 0.0634 |
| 20 | 4.058 | 1.353 | 0.08454 |
| 30 | 6.087 | 2.029 | 0.1268 |
| 60 | 12.17 | 4.058 | 0.2536 |
| 100 | 20.29 | 6.763 | 0.4227 |
| 125 | 25.36 | 8.454 | 0.5283 |
| 200 | 40.58 | 13.53 | 0.8454 |
| 250 | 50.72 | 16.91 | 1.057 |
| 500 | 101.4 | 33.81 | 2.113 |
Recipe conversion mistakes
- Using a US cup on an Australian recipe, or the reverse. The 250 mL metric cup is 5.7% larger. In a recipe with three cups of liquid the gap is over 40 mL.
- Counting Australian tablespoons as 15 mL. For baking powder, salt or gelatin, a 20 mL tablespoon is a third more than a 15 mL one, which can change the result.
- Converting flour by cups to grams with someone else’s density. Weigh your own cup of flour once, or follow a recipe that gives grams.
- Treating a fluid ounce as an ounce of weight. Eight US fluid ounces of honey weigh noticeably more than eight ounces; fluid ounces measure space, not mass.
Many measuring spoons and cups have their size stamped on the handle. Check yours before converting: if your tablespoon reads 15 mL and the recipe is Australian, use one tablespoon plus one teaspoon (15 + 5 = 20 mL) for each tablespoon asked for.
Sources
- 21 CFR 101.9 Nutrition labeling of food, paragraph (b)(5)(viii), Electronic Code of Federal Regulations (eCFR).
- Metric Kitchen - Culinary Measurement Tips, National Institute of Standards and Technology.
- Guide for the Use of the International System of Units (SI), NIST Special Publication 811, Appendix B, National Institute of Standards and Technology.
- Safe Food for Canadians Regulations (SOR/2018-108), section 241, Justice Laws Website, Government of Canada.