1 cup of buttermilk in grams — 245 g.

Why 245 g per cup

Buttermilk's density is essentially the same as whole milk (245 g/cup) — the cultured fermentation thickens the texture but doesn't change the mass significantly.

Dairy densities cluster slightly above water (1 g/ml) because of milk solids and fat content. Whole milk and buttermilk both run ~245 g/cup; heavy cream is lighter at ~232 g/cup because the higher fat content means lower density (fats are less dense than water).

The most accurate way to measure buttermilk

For recipes where the outcome matters — bakes, doughs, anything leavened — measure buttermilk on a kitchen scale set to grams. Set the bowl on the scale, press tare to zero, then add until the readout matches the gram value the recipe calls for. This removes the largest source of cup-to-cup variation: how you scoop.

The cup-based numbers on this page assume the “spoon and level” method — fluffing the ingredient in its container, spooning it into the cup, and levelling the top with a straight edge. Scooping directly with the cup packs more in, and can push the gram value up by 20-30 % for fluffy ingredients like flour and cocoa.