Vital wheat gluten

One US cup of vital wheat gluten weighs between 120.2 and 144 grams, depending on how the cup is filled and which source measured it. That range is the answer; a single number would not be. Every figure behind it is below, with the method each source used.

Also called wheat gluten, pure wheat gluten, wheat protein isolate, seitan flour.

Two sources publish figures for a cup of vital wheat gluten and they differ by 20%. This entry publishes the range they cover rather than a single figure, at low confidence, because the variation reflects real differences between manufacturer products rather than a measurement error.

King Arthur's Ingredient Weight Chart publishes 2 tablespoons at 18 g, extrapolating to 144 g per cup (0.6086 g/mL) using the 16 tablespoons per cup relation. USDA Branded Foods records for vital wheat gluten from different manufacturers show a range from approximately 120 g per cup (Bob's Red Mill, UPC 039978043221, 127 g per metric cup converted to US customary) to approximately 144 g per cup (UPC 074333371205, 152 g per metric cup converted). The heavier USDA Branded figure agrees with King Arthur exactly; the lighter Bob's Red Mill figure is 17% below both.

USDA SR Legacy record FDC 168147 (Vital wheat gluten) exists as a reference but publishes only per-100g nutritional data, with no cup portion attached. This is a common pattern for concentrated protein ingredients in SR Legacy: the reference is measured by weight in the lab, and volume portions are added only for foods consumers typically measure by volume. USDA Branded Foods fills the cup-portion gap through manufacturer-submitted label data, which is why brand differences appear at the cup level even though the underlying nutritional data is consistent per gram.

The physical reason for the brand variation is grind fineness and resulting packing density. Vital wheat gluten is produced by washing wheat flour to remove starch, then drying and grinding the concentrated gluten protein. Different manufacturers use different final grinds. Finer grinds trap more air when scooped, producing lower bulk density; a fluffier product weighs less per cup even though the underlying protein material is chemically identical. This is the same physical mechanism that causes all-purpose flour to publish as a range across dip-and-sweep and spoon-and-sweep methods, but here the variable is the manufacturer's grind specification rather than the user's filling technique.

Vital wheat gluten sits in the milled category alongside flours and cocoa powder. The 10% category tolerance applies here, and the 20% gap between the low and high figures clearly exceeds it, hence the range publish. Home bakers who add vital wheat gluten to bread doughs, typically 1 to 2 tablespoons per cup of flour to boost protein and improve rise in whole wheat or specialty breads, should weigh rather than measure by volume: a 17% error in the gluten quantity meaningfully changes dough hydration and gluten development.

Not to be confused with high-gluten flour, a separate product covered by King Arthur at 120 g per cup. High-gluten flour is wheat flour with elevated gluten content (approximately 13-14% protein), used for chewy breads and bagels. Vital wheat gluten is 75-80% protein by mass, an order of magnitude more concentrated than any wheat flour, and used as an additive rather than a base flour. The two are not interchangeable.

No standards body publishes a bulk density for vital wheat gluten. Codex Alimentarius covers wheat and wheat protein composition but not physical density. Two authoritative sources with real brand variation, so this entry is held at low confidence and range published until either a third authoritative source resolves the split or SR Legacy adds cup-portion data for FDC 168147.