Red Pepper Flakes

One US cup of red pepper flakes weighs between 79.9 and 96.4 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 red pepper flakes, crushed red pepper, red chili flakes, chili pepper flakes, pizza pepper, crushed red pepper flakes.

One cup of crushed red pepper flakes weighs somewhere between 80 and 96 grams (0.338-0.407 g/mL). The site publishes this as a range at LOW confidence because the two direct-measurement sources — Chef's Resources spice table at 79.9 g/cup and USDA Branded Food record for a specific crushed red pepper product at 96 g/cup — disagree by 20% and both figures are legitimately measured. The variance is real product variance, not measurement error.

Red pepper flakes (also called crushed red pepper or, informally, pizza pepper) are dried hot chili peppers crushed into irregular flakes with the seeds typically retained. Common commercial products blend multiple pepper varieties (cayenne, ancho, bell) rather than using a single cultivar, and the seed-to-pericarp ratio varies substantially across brands. Retained seeds intensify both heat (seeds carry more capsaicin per unit mass) and density (seeds are more compact than the papery pericarp flakes). Coarser crushes leave more air per cup; finer crushes pack denser. These two variables together account for the 20% spread across sources.

Red pepper flakes are distinct from three related products the site treats separately. Ground cayenne pepper is finer, denser, more uniform, and typically single-cultivar; the site's `cayenne-pepper` entry lives at 85-101 g/cup. Chili powder is a blend that includes cumin, oregano, garlic, and other spices in addition to ground chili — different flavor profile, different density (~107 g/cup), different intended use. Sweet paprika is ground from a different, non-spicy Capsicum cultivar and reads about 109 g/cup with none of the heat. Substituting any of these for red pepper flakes by volume produces a wildly different result in flavor and heat, well beyond any density concern.

Sub-gram serving labels on retail products cannot be trusted for red pepper flake density. McCormick Crushed Red Pepper Flakes lists 1 tsp = 0.32 g, which reads out to about 15 g/cup — five times less than every other source and physically implausible for a coarse dried product. This is the classic S19-catalogued sub-gram rounding artifact: FDA labels can round a serving mass to 0, 0.5, or 1 g, so any spice used in less-than-1-g portions per label serving has an implied density that swings wildly under rounding. Labels are useful for identifying the product; they are not useful for density.

For practical cooking, the density spread matters less than the Scoville heat spread, which can be 2-3x across brands (10,000 SHU for a mild pizza-parlor blend vs 40,000 SHU for a hot Calabrian-style blend). Weight-critical applications like calibrated hot sauces, competition BBQ rubs with tight ratios, and commercial canning brines should weigh the specific product being used and note both mass per tsp and estimated Scoville heat. Everyday cooking (a pinch on pizza, a shake into pasta sauce) is unaffected by density variance — the recipe is tuned to taste anyway.

Storage and freshness: whole flakes retain aromatic volatile oils longer than ground cayenne because the larger particle surface-to-volume ratio slows oxidation. Peak potency lasts 6-12 months after opening in a cool, dark cupboard; older flakes lose heat and aroma but not density.