Cup sizes by country
A cup is not one measurement. The US legal cup is 240 ml, the Australian metric cup is 250 ml and the old British imperial cup is 284.1 ml. That is a spread of nearly 20 percent between the largest and the smallest, so a recipe written in one country and measured in another can be out by a fifth before you have even picked up the flour.
Every cup standard in millilitres
| Cup standard | Volume | Compared with a US cup | Where you meet it |
|---|---|---|---|
| US legal cup | 240 ml | The reference | United States, nutrition labels and most modern recipe writing |
| US customary cup | 236.6 ml | -1.4% | United States, the strict legacy definition |
| Metric cup | 250 ml | +4.2% | Australia, New Zealand, and much of continental Europe |
| Imperial cup | 284.1 ml | +18.4% | United Kingdom, historical recipes |
| Canadian cup | 227.3 ml | -5.3% | Canada, pre-metrication recipes |
| Japanese cup | 200 ml | -16.7% | Japan, modern cooking |
Volumes are exact definitions rather than kitchen roundings. The US customary cup is eight US fluid ounces of 29.5735295625 ml each; the imperial cup is ten imperial fluid ounces of 28.4130625 ml each.
The same ingredient weighed in every cup
Because grams are grams everywhere, the cleanest way to see the difference is to weigh one ingredient in all six cups. Each row below uses that ingredient density and simply changes the volume it is poured into.
| Ingredient | US legal 240 ml | US customary 236.6 ml | Metric 250 ml | Imperial 284.1 ml | Canadian 227.3 ml | Japanese 200 ml |
|---|---|---|---|---|---|---|
| All-Purpose Flour | 125 g | 123 g | 130 g | 148 g | 118 g | 104 g |
| Granulated Sugar | 200 g | 197 g | 208 g | 237 g | 189 g | 167 g |
| Butter | 227 g | 224 g | 236 g | 269 g | 215 g | 189 g |
| Milk | 244 g | 241 g | 254 g | 289 g | 231 g | 203 g |
| Water | 240 g | 237 g | 250 g | 284 g | 227 g | 200 g |
| Honey | 340 g | 335 g | 354 g | 403 g | 322 g | 283 g |
Read one row across and you can see the practical size of the problem. Flour swings by roughly 44 grams between the Japanese and imperial cups; honey, being nearly three times as dense, swings by about 120 grams over the same range.
Which cup does my recipe mean?
Nine times out of ten, the answer follows the origin of the recipe. An American blog, an American cookbook or anything written for a US audience means the 240 ml legal cup, or its close cousin the 236.6 ml customary cup, and the difference between those two is small enough to ignore. An Australian or New Zealand recipe means the 250 ml metric cup. A Japanese recipe means 200 ml.
British recipes are the easy case in reverse: they normally give weights in grams already, because British home baking switched to scales decades ago. If you are looking at a British recipe that does quote cups, it is either an older book using the 284.1 ml imperial cup or, far more often, a modern site quietly reprinting an American recipe. A quick sanity check settles it: if the recipe also lists ounces and pounds, treat it as American.
Canada sits in the middle. Modern Canadian recipes use the US cup or metric weights, but pre-metrication Canadian cookbooks use the 227.3 ml imperial-based cup, which is smaller than every other cup on this page except the Japanese one.
Does the cup standard actually matter?
Less than people fear, and much less than the ingredient does. The full range of cup standards spans about 42 percent, from the 200 ml Japanese cup to the 284.1 ml imperial cup. The range between ingredients is far wider: a cup of panko breadcrumbs weighs 50 grams and a cup of honey weighs 340 grams, a difference of nearly 600 percent from the same measuring cup.
The way you fill the cup also competes with the standard for influence. Flour scooped straight from the bag can carry 20 percent more than flour spooned in and levelled, which is the same order of error as using the wrong country's cup. That is why the reliable answer to all of this is a kitchen scale: a gram is a gram in every country and it does not care how you packed it.
Where the standard does matter is in liquids and in big quantities. Water, milk and oil are measured accurately by volume, so a 250 ml cup really does deliver 4.2 percent more liquid than a 240 ml one, every time, and across the five cups of liquid in a large batch of bread that adds up to a noticeably wetter dough.
Where these numbers come from
The cup volumes on this page are definitions rather than measurements. The us legal cup of 240 ml is fixed by the US Food and Drug Administration for nutrition labelling in 21 CFR 101.9(b)(5)(viii), the same rule that defines a teaspoon as 5 ml and a tablespoon as 15 ml. The US customary and imperial cups follow from their fluid ounce definitions, and the metric and Japanese cups are round metric figures by design.
The gram figures come from each ingredient's density as used across this site, which is anchored on widely published reference weights: butter at 227 grams per US cup, water at 240, all-purpose flour at about 125 and granulated sugar at about 200. Those anchors sit within the range that USDA FoodData Central and the King Arthur Baking ingredient weight chart give, but the two do not agree with each other and neither should be read as the single correct answer. King Arthur measures against a 227 ml cup and publishes 120 grams for a cup of flour where this site uses 125, a gap of about four percent, which is smaller than the difference between scooping and spooning the same flour. That is the honest state of ingredient densities: published values differ by a few percent because packing differs, which is the argument for a kitchen scale.
Frequently asked questions
How many grams is 1 cup in the UK?
British recipes almost always give grams directly, so the honest answer is that the UK does not really use cups any more. Where an older British recipe does say cups it means the imperial cup of 284.1 ml, which is 18 percent larger than a US cup. An imperial cup of flour is about 148 grams and of granulated sugar about 237 grams, against 125 and 200 grams for the US cup.
How many grams is 1 Australian cup?
An Australian cup is the metric cup, exactly 250 ml, so it holds 4.2 percent more than a US cup. That works out at about 130 grams of all-purpose flour, 208 grams of granulated sugar and 254 grams of milk. Australian recipes also use a 20 ml tablespoon rather than the 15 ml one used elsewhere, which causes more trouble than the cup itself.
Is an American cup 240 ml or 237 ml?
Both figures are correct for different definitions. The US legal cup, fixed by the FDA for nutrition labelling, is exactly 240 ml. The older US customary cup is 8 US fluid ounces, which is 236.588 ml, usually rounded to 237. The 3.4 ml difference is about 1.4 percent, far smaller than the variation you get from how firmly you pack a cup of flour.
Does the cup standard matter more than the ingredient?
No, the ingredient matters far more. The widest gap between cup standards is about 42 percent, between the Japanese 200 ml cup and the imperial 284 ml cup. The gap between a cup of flour and a cup of honey is roughly 170 percent. Getting the ingredient right is the big win; getting the cup standard right is the polish on top.
Which cup does CupsToGrams use?
The US legal cup at 240 ml, because it is the definition most recipe writing assumes and the one the FDA sets for nutrition labels. Every gram figure on this site is calculated from that volume. If your recipe uses a different cup, the comparison table on this page scales the same densities to that standard.