You follow a US recipe to the letter, measuring cup after cup, and somehow your cake is denser than expected. The problem might not be your technique. It could be your cup.
US and UK recipes use the same words for measurements, but not always the same sizes. A "cup" in New York holds less than a "cup" in London or Sydney. A tablespoon in Australia is a third bigger than one in the UK. These differences are small enough to miss but large enough to matter, especially in baking.
US vs UK Cup Sizes
The metric cup, used in the UK, Australia, Canada, and New Zealand, holds 250 ml. The US cup holds 240 ml. That's a 10 ml difference per cup.
For a single cup of flour, the gap is small: 1 metric cup of plain flour weighs 125 g, while 1 US cup weighs roughly 120 g. Scale that across a recipe calling for 3 cups and you're off by 15 g before you've touched the butter.
There's a third size worth knowing: the old UK imperial cup, which held 284 ml (10 fluid ounces). You may encounter it in very old British cookbooks. Modern UK recipes no longer use it.
| Region | Cup size |
|---|---|
| US | 240 ml |
| UK (modern) | 250 ml |
| Australia | 250 ml |
| Canada | 250 ml |
| New Zealand | 250 ml |
| UK (old imperial) | 284 ml |
This site uses the metric cup (250 ml) for all conversions. If you're working from a US recipe and measuring in cups, the cups to grams converter lets you enter the US cup value and get grams back.
Tablespoons and Teaspoons: Where It Gets Tricky
Teaspoons are the easy one: 5 ml everywhere. The UK, US, Australia, and Canada all agree on this.
Tablespoons are a different story.
A UK tablespoon holds 15 ml. A US tablespoon holds 14.79 ml (close enough that most recipes treat them as equal, but worth knowing when precision matters). An Australian tablespoon holds 20 ml, a third larger than either. Use the wrong size for baking powder or salt and you will notice.
This site uses 20 ml tablespoons. There are 12.5 tablespoons per metric cup (250 ml divided by 20 ml). If you're following a UK or US recipe that specifies tablespoons, the values shown here reflect the 20 ml size.
| Measurement | UK | US | Australia |
|---|---|---|---|
| 1 cup | 250 ml | 240 ml | 250 ml |
| 1 tablespoon | 15 ml | 14.79 ml | 20 ml |
| 1 teaspoon | 5 ml | 5 ml | 5 ml |
For ingredients where tablespoons appear regularly, like sugar or baking powder, the difference between a 15 ml and 20 ml tablespoon can shift a recipe's balance noticeably.
Pounds, Ounces, and Fluid Ounces
US recipes lean heavily on ounces, pounds, and fluid ounces. A UK or Australian baker picking up an American recipe will often see "8 fl oz of milk": that's 236.6 ml, not the 250 ml metric cup they're used to.
There's a wrinkle here too: a US fluid ounce is 29.57 ml, while a UK fluid ounce is 28.41 ml. The difference is roughly 4% per fluid ounce. This site's converters use US fluid ounces (1 metric cup = 8.454 fl oz), so UK readers should keep that in mind when converting liquid ingredients.
Dry ounces are used in the US more than in the UK. UK recipes have largely shifted to grams for dry ingredients, though older recipes and American imports still call for ounces. One dry ounce is approximately 28.35 g regardless of country.
Tip: weighing ingredients in grams removes all of this ambiguity. Grams are grams everywhere.
Self-Raising vs All-Purpose Flour
One more difference that catches people out: what the UK calls self-raising flour, the US calls self-rising flour. They're the same thing (plain flour with baking powder and salt added), but US recipes typically use all-purpose flour and list the leavening separately.
If you're converting a UK recipe that calls for self-raising flour and can only find all-purpose, the self-raising flour calculator works out the ratios for you.
For plain flour conversions between cups and grams, the plain flour converter handles both metric and US cups.
Stop Guessing, Start Weighing
The real solution to all of this is a kitchen scale. Once you work in grams, cup sizes, tablespoon volumes, and regional standards stop mattering. A recipe that says "125 g of flour" means the same thing in every kitchen in the world.
The converters on this site work from metric cups (250 ml) by default, with US cups available as a second option. Start with the cups to grams converter if you're working from a US recipe, or browse by ingredient to see the full breakdown for whatever you're measuring.