How do I convert cups to grams?

Cup measures work well for liquids and badly for anything that can be packed. The variation is not a rounding issue — it is enough to change whether a cake works, which is why the answer is usually to stop converting.

Step by step

1. Understand why one number cannot exist.A cup measures the space something occupies. A cup of feathers and a cup of lead weigh differently. Every ingredient therefore has its own conversion, and dense ones differ enormously from light ones.
2. Learn the handful that come up constantly.Plain or self-raising flour about 125g, granulated or caster sugar about 200g, brown sugar packed about 220g, butter 227g, water or milk 240g, oil about 220g, rolled oats about 90g, icing sugar about 120g.
3. Treat flour as the unreliable one.Scooping a cup straight from the bag compacts the flour and can give 150g or more where the recipe intended 125g. That is a fifth more flour, which is the difference between a light sponge and a dry one.
4. Use the spoon-and-level method if you must use cups.Spoon flour loosely into the cup and level the top with a knife. Never scoop, never tap the cup down. It is the closest cups get to consistent.
5. Check which country's cup the recipe means.A US cup is 240ml, an Australian cup 250ml, and a UK recipe using cups usually means the US one. The difference is small but compounds across a recipe.
6. Use volume for liquids without worrying.Water, milk and stock convert cleanly — a cup is 240ml and 240g. Liquids are where cup measures are genuinely fine.
7. Weigh sticky things instead of measuring them.Honey, syrup, treacle and peanut butter cling to a cup and leave a meaningful proportion behind. Weighing straight into the bowl avoids the waste and the washing up.
8. Buy scales and use the tare button.Digital scales cost very little. Put the bowl on, press tare, add the first ingredient, tare again, add the next. One bowl, no measuring cups, and accurate.
9. Convert the recipe once and write it down.If you use a cup recipe repeatedly, do the conversion once, note the grams on the recipe, and never think about it again.
10. Keep cups for cooking, not baking.A stew does not care whether the tomatoes were 380g or 420g. A cake does. The precision matters where the chemistry matters.

Tips

• Baking recipes given in grams are almost always more reliable than the same recipe in cups, because the author measured rather than estimated.
• Scales that switch between grams and ounces save converting older British recipes as well.
• For butter, the wrapper markings are accurate enough — a US stick is 113g, half a cup.

Common mistakes

• Scooping flour with the measuring cup — It compacts the flour and can add 20% more than the recipe intended, which is enough to make a cake dry and dense.
• Using one conversion figure for everything — Cups measure volume, so every ingredient has its own weight. A cup of sugar weighs well over half as much again as a cup of flour.

If it doesn't work

Questions people ask