Why bakers weigh
A cup of flour weighs different amounts depending on how it was filled: scooped and packed, or spooned in loosely and levelled. A gram is always a gram. King Arthur recommends weighing ingredients with a digital scale for the best results.
Common cup weights
From King Arthur’s chart, per US cup:
| Ingredient | Grams |
|---|---|
| All-purpose flour | 120 |
| Bread flour | 120 |
| Granulated sugar | 198 |
| Brown sugar, packed | 213 |
| Confectioners’ (powdered) sugar, unsifted | 113 |
| Oats, old-fashioned or quick | 89 |
Use the recipe’s own number
Publishers don’t agree on flour. USDA’s FoodData Central lists a cup of all-purpose flour as 125 g, against King Arthur’s 120 g. For a recipe with 3 cups, that’s 375 g or 360 g.
If a recipe states its own conversion, follow it, since that’s how the recipe was tested. A metric cup also holds more than a US cup; see US, UK and metric cups.