How Many Grams in a Cup of All-Purpose Flour?

All-purpose flour is the workhorse of home baking, milled from a blend of hard and soft wheat to balance protein and starch. One US cup weighs approximately 120 grams when measured using the spoon-and-level method. This density sits between lighter cake flour and heavier bread flour, making it versatile for cookies, muffins, quick breads, and many yeast recipes when bread flour is unavailable.

Flour compresses easily, which is why two bakers measuring one cup can differ by 30 grams or more. To measure accurately, fluff the flour in its container with a spoon, gently spoon it into a dry measuring cup until heaped, then level with a straight edge without packing or tapping the cup. Never scoop directly from the bag with the measuring cup—that compacts flour and can push a single cup past 140 grams.

Common mistakes include using a liquid measuring cup for dry flour, skipping the fluffing step, and converting weight recipes to volume without adjusting for brand differences. European and American all-purpose flours differ slightly in protein; if a recipe fails, check whether it was written for US or UK flour and weigh ingredients for consistency.

Store all-purpose flour in an airtight container in a cool, dry place. Whole-grain versions spoil faster due to oil in the germ; white all-purpose flour keeps six to eight months at room temperature or up to a year refrigerated. For substitution, bread flour adds chewiness in yeast breads; cake flour yields softer cakes but requires recipe adjustments.

When scaling recipes, multiply 120 grams by the number of cups needed rather than doubling volume measures—especially for large batches where small per-cup errors compound. Professional bakers and pastry chefs rely on metric weights because flour humidity changes density overnight in open kitchens. If your kitchen scale reads in ounces, one cup of all-purpose flour equals roughly 4.2 ounces. Reference charts for half cup (60g), third cup (40g), and quarter cup (30g) make quick adjustments without recalculating from scratch every time you halve a recipe.

Bookmark common fractions for daily baking: three-quarters cup equals 90 grams, one-third cup about 40 grams, and two-thirds cup roughly 80 grams. These anchors help when you scale family recipes or adapt cookbooks that only list cups without gram equivalents.