Weight vs volume

Volume measures such as cups depend on how an ingredient is packed, sifted or scooped, so the same cup of flour can hold quite different amounts. Weight does not change with packing.

The U.S. National Institute of Standards and Technology describes weighing as more precise and consistent than measuring by volume, so recipes come out the same each time. It also calls weighing faster and more efficient, especially for small amounts or sticky items like honey or molasses, and notes that it saves washing multiple measuring cups and spoons.

In baking this matters because small differences in ingredient amounts can change texture and taste. Bakers who use a scale can follow recipes written in grams exactly, scale a batch up or down without awkward fractions, and measure straight into the mixing bowl by taring the scale between additions.