Why a cup of flour isn’t a cup of sugar
Cups measure space, not weight. That small difference explains a lot of dense cakes.
A measuring cup tells you how much room an ingredient takes up. A scale tells you how heavy it is. Because ingredients pack differently, the same cup can hold very different weights.
| 1 US cup of… | Weighs about |
|---|---|
| All-purpose flour, spooned and levelled | 120 g |
| Granulated sugar | 198 g |
| Butter | 227 g |
| Water | 237 g |
Flour weights follow King Arthur Baking’s published chart. Scooping flour straight from the bag presses it down and can add 20% or more, which is the most common reason a cake turns out heavy.
Cups are not all the same size
A US cup holds 236.6 mL, while recipes from Australia, New Zealand and many other countries use a 250 mL metric cup. The difference is small for one cup and noticeable over four.
What to do about it
- Weigh flour and sugar when a recipe gives grams.
- When it only gives cups, spoon the flour in and level it with a knife.
- Scaling a recipe up or down? Let the calculator tidy the spoons and cups for you.
Try it yourself