Sourdough Bread Flour Cups to Grams Converter

Sourdough depends on ratios — hydration, salt, and starter are all percentages of flour. If your flour weight is off, every ratio is off with it. Weighing in grams pins those ratios down so your loaf comes out the same each time.

Grams are also more precise than cups (1 gram versus a rough cup line) and faster in practice — you can weigh everything into one bowl on a scale, zeroing between each addition.

The biggest source of error with cups is how you fill them. Dipping the cup into the bag packs the flour down, so a "cup" can weigh anywhere from 120g up to 150g or more — a 20–30% swing that can wreck a bread recipe.

The standard 120g-per-cup weight assumes you spoon flour lightly into the cup and level it off with a knife. When in doubt, weigh — it sidesteps the problem entirely.

Bread flour and all-purpose are almost identical by weight, around 120g per cup — they differ in protein, not density. Whole wheat is a little lighter at about 113g, and rye lighter still at around 102g because of how the bran sits.

The converter keeps each flour separate so you always get the right weight, and the reference chart on the calculator lists them side by side.

If you don't have a scale, fluff the flour in the bag first, spoon it lightly into the cup without tapping or packing, then level the top with the back of a knife. That's the method the 120g-per-cup standard assumes.

Then use this converter to turn those cups into grams — so you can follow gram-based bread recipes and pair the result with the baker's percentage calculator.