Oat Bran

One US cup of oat bran weighs between 80 and 120 grams (2.8 to 4.2 ounces), depending on how the cup is filled and which source measured it. Use 100 grams (3.5 ounces) if the brand is unknown; Quaker is 80 g and Bob's Red Mill 120 g. Every figure behind it is below, with the method each source used.

Also called raw oat bran, oat bran cereal, oat bran hot cereal, uncooked oat bran.

A cup of dry oat bran weighs anywhere from 80 to 120 g (2.8 to 4.2 oz), depending mostly on the brand. Quaker's oat bran is 80 g per cup, USDA's raw oat bran 94 g, King Arthur says 106 g and Bob's Red Mill's 120 g. That is far beyond the 10% tolerance, so this entry publishes the range.

Oat bran is the outer layer of the oat groat, milled away from the starchy center. It is high in protein (17%) and soluble fibre, the beta-glucan behind the oat heart-health claim, and is eaten as a hot cereal and added to muffins, breads and smoothies. Brands mill it differently: some sell flaky, coarse bran, others a finer, almost floury meal.

USDA SR Legacy "Oat bran, raw" (FDC 168872) lists 1 cup at 94 g. USDA's Quaker and Mother's oat bran record (FDC 174626) lists 1/2 cup at 40 g, 80 g per cup, and Quaker's current label says the same. Bob's Red Mill prints 1/3 cup at 40 g on four different oat bran products, 120 g per cup. King Arthur's chart lists oat bran at 1/2 cup = 53 g, 106 g per cup, inside the range, so it is not a correction.

The labels are better evidence than usual here, but they need reading carefully. US hot cereal labels all use the same 40 g serving, the reference amount for dry hot cereal, so the grams never change; what each brand chooses is the volume that 40 g fills, and that volume reflects its own product. Quaker's 40 g fills half a cup, Bob's only a third. Kroger's oat bran, at 35 g per 1/3 cup, works out to 105 g per cup, between the two.

The physical check is about particle shape. Coarse, flaky bran stacks loosely with a lot of air, like wheat bran, which weighs only about 60 g per cup on this site; a fine meal fills the gaps and packs nearly as densely as a whole-grain flour. Oat bran sits between those, and each brand's grind decides where. Quick oats and rolled oats, for comparison, weigh 80-90 g per cup.

Practical guidance: weigh oat bran, and if a recipe gives it in cups, assume it was written for whatever brand the author had. For Quaker or Mother's, use 80 g per cup; for Bob's Red Mill, 120 g; for an unknown brand, about 100 g. A single 40 g serving for hot cereal is the same weight whichever brand you buy, so for breakfast, measure by weight and the volume does not matter.