Peanuts

One US cup of peanuts weighs 146 grams. Going the other way, 100 grams is about 0.68 cups.

Also called shelled peanuts, raw peanuts, whole peanuts, groundnuts, peanut kernels.

Two sources agree within tolerance. USDA FoodData Central FDC 172430 (Peanuts, all types, raw, SR Legacy) publishes 1 cup at 146 g, implying a density of 0.6171 g/mL. King Arthur's Ingredient Weight Chart lists 'Peanuts (whole, shelled)' at 1 cup = 142 g, implying 0.6003 g/mL. The gap between them is 2.82%, well inside the 5% tolerance that would apply to a tightly-defined kernel, let alone the 10% milled tolerance for whole and chopped nuts, so this entry publishes USDA's figure of 146 g per cup and names both sources. Neither source names a specific filling method, and both figures are for the shelled, uncooked kernel.

Peanut kernels pack denser than the tree nuts published on this site. For comparison, pistachios publish at 123 g per cup, hazelnuts at 135 g per cup, and peanuts at 146 g per cup. The pattern tracks with kernel size and shape: peanut kernels are smaller than hazelnut kernels (typically 10 to 15 mm long) and typically split into paired half-ellipsoids with one flat cleavage face. The flat face allows flat-to-flat contact between neighboring kernels, which reduces air-gap volume more than the round-on-round contact of spherical hazelnut kernels. USDA's own reference documentation notes that a loosely filled cup can vary by 20 to 30 g depending on whether peanuts are whole, halved or chopped, an unusually wide fill-method sensitivity that reflects the shape variability.

Peanuts are botanically legumes (Fabaceae family) rather than tree nuts, and are the seed of Arachis hypogaea. USDA and the food industry classify them with nuts for nutritional and culinary purposes because their fat, protein and use profile matches tree nuts more closely than beans or lentils. This site places peanuts in the milled category alongside other whole and chopped nuts because the category rule tracks physical packing behavior rather than botanical family: whole peanut kernels pack by scoop with air gaps in the same manner as tree-nut kernels. The peanut allergen risk is separate from tree-nut allergen risk and readers with either allergy should note the distinction.

Peanut butter, published on this site in the fat category, is a fundamentally different product. It is a smooth homogeneous paste of ground peanuts with the fat phase continuous, and its density behavior is set by the fat and moisture content rather than by kernel packing. Chopped or roasted peanuts pack differently from raw whole peanuts and are separate products that would earn their own entries when a second authoritative source becomes available. USDA has FDC records for dry-roasted, oil-roasted, boiled and honey-roasted peanuts, but King Arthur does not list variant preparations.

Product variants: raw versus dry-roasted peanuts differ by approximately 4% in moisture, which slightly increases apparent density after roasting but rarely crosses the milled tolerance. Salted versus unsalted differs by 1 to 2% by weight from added sodium, well inside measurement noise. Spanish, Runner, Virginia and Valencia are peanut cultivars that show small differences in kernel size and cup mass but sit within a few percent of the all-types average.

No standards body publishes a bulk density for peanuts. Codex Alimentarius has a standard for peanuts covering moisture content, defect tolerances and aflatoxin limits but not physical density. Two independent authoritative sources agree within tolerance, so this entry is held at medium confidence. A third independent source, such as a professional culinary reference or a producer's laboratory measurement, matching within tolerance would move it to high confidence.