“1 cup” doesn’t mean the same volume everywhere. A cup measured in the US isn’t the same size as a cup measured in Australia or the UK, and even within the US there are two slightly different definitions in everyday use. None of the gaps are huge on their own — but they add up fast once you’re baking in bulk.
The short answer
Three cup sizes show up in baking:
- US food-label cup (240ml) — the value defined for US nutrition labeling and the default this site uses for recipe conversions.
- US customary cup (236.588ml, rounded to 236ml) — the traditional volume equal to 8 US fluid ounces.
- Metric cup (250ml) — used in Australia, New Zealand, and some UK recipes.
The gap between the smallest and largest is only about 14ml — roughly a tablespoon — but because grams-per-cup values scale with volume, that difference shows up in every ingredient you measure.
How much this actually changes on your scale
| Ingredient | US cup (240ml) | US customary (236ml) | Metric cup (250ml) |
|---|---|---|---|
| Flour | 120g | 118.3g | 125g |
| Granulated sugar | 198g | 195.2g | 206.3g |
| Butter | 227g | 223.8g | 236.5g |
| Milk | 244g | 240.5g | 254.2g |
For a single cup of flour, the 240ml-to-metric gap is only a few grams — easy to ignore in a weeknight batch of cookies. Scale that up across a large bread formula, however, and the accumulated difference can visibly change a dough’s hydration.
grams = cups × grams per cup (for that cup size)
Always check which "cup" a recipe means before scaling it up
Which cup does this site use — and why
We use the 240ml US food-label cup as the default grams-per-cup basis throughout this site. The 236.588ml US customary cup and 250ml metric cup values are derived from the same ingredient measurement and are also available for readers using traditional US measures or Australian and New Zealand recipes. See our cup sizes reference for the full definitions.
Examples across ingredients
- A metric-cup recipe (Australia/NZ) calling for 1 cup of butter uses 236.5g, compared with 227g on this site’s 240ml basis.
- 1 cup of milk is 244g on the 240ml basis and 240.5g in a US customary cup.
- 1 metric cup of granulated sugar is 206.3g, versus 198g on the 240ml basis; the difference becomes more important when a recipe is scaled.
Convert with the right cup size
Enter a cup amount and get the gram equivalent for any ingredient on this site.
When the difference actually matters
For a single cup or two in a casual recipe, the gap between cup standards is small enough to ignore — a few grams of flour or sugar won’t ruin a batch of muffins. It matters more when:
- You’re scaling a recipe up, since small per-cup errors multiply with every cup added.
- The recipe came from a different country than your measuring cups, especially Australian or British recipes measured with US cups.
- The recipe is precision-sensitive, like bread, candy, or laminated dough, where small ratio shifts are visible in the final result.
For the full range of gram values across cup sizes and amounts, see the grams to cups conversion chart, or check our full methodology for how each cup-size value was measured and verified.
When a recipe's origin is unclear, weighing in grams sidesteps the whole question — a gram is the same everywhere in the world, unlike a cup.
Frequently asked questions
Is a US cup 236ml or 240ml?
Both figures exist, but they describe different conventions. A US customary cup is exactly 8 US fluid ounces, about 236.588ml. US nutrition-label rules define a cup as 240ml; that is also this site's default conversion basis.
What is a metric cup?
A metric cup is exactly 250ml. It's the standard used in Australia, New Zealand, and some UK recipes, rather than the 236–240ml US definitions.
Does the UK use the metric cup?
UK recipes most often use weight (grams) rather than cups at all. When a UK recipe does specify cups, it typically follows the 250ml metric cup rather than the US cup.
How much does the cup-size difference matter in a normal recipe?
For most everyday baking — cookies, cakes, pancakes — the few grams of difference between cup standards won't be noticeable. It matters more in bread, candy, and any recipe you're multiplying by a large factor, where small per-cup differences add up. See the flour grams to cups page for the exact numbers across all three cup sizes.