Prunes

One US cup of prunes weighs 174 grams. Going the other way, 100 grams is about 0.57 cups.

Also called prunes, dried plums, pitted prunes, dried pitted prunes, california prunes, prunus domestica dried.

Prunes publish at 174 grams per cup with medium confidence, anchored by USDA FoodData Central and cross-validated against Sunsweet, the dominant US commercial prune brand. USDA FDC entry 168162 (Plums, dried (prunes), uncooked) publishes a direct cup portion of 174 g/cup pitted (density 0.7354 g/mL), with supplemental per-prune figure of 10 g and 3-prune figure of 30 g for internal consistency. Sunsweet Amaz!n Pitted Prunes label 40 g per serving of 5 regular prunes (8 g per prune) and 40 g per 7 bite-size prunes (5.7 g per prune), which back-calculates to approximately 160-176 g/cup depending on prune count fitting the cup — bracketing USDA's 174 figure within milled tolerance.

Prunes are dried plums, specifically the freestone European plum cultivar (Prunus domestica) that has a high sugar content and firm flesh suitable for drying without fermentation. Most commercial prunes are grown in California from cultivars descended from the French d'Agen plum, brought to the US by Louis Pellier in 1856. The California Prune Board rebranded prunes to dried plums in 2000 to counter negative associations with elderly consumers and constipation relief, though prunes remains the more common name in cooking, baking, and clinical health research. Sunsweet Growers, a California grower cooperative founded in 1917, holds roughly 40 percent of the US prune market and sets the de facto industry quality reference.

Physical mechanism for the 174 g/cup density: prunes are dried fruit with moderate moisture content (approximately 31 percent water retained during controlled drying) and a deformable soft-solid texture. Unlike small crystalline dried fruits such as raisins or dried cranberries, prunes retain their pit-cavity shape after pitting and pack into a cup with significant air voids at the pit-cavity openings. The 174 g/cup figure reflects average commercial pitted prunes measured spooned-and-leveled. Compressing prunes into the cup (as recipes calling for packed prunes sometimes specify) would push the density higher, potentially toward 200 g/cup for firmly packed prunes.

Product-form variance: regular pitted prunes (approximately 8 to 10 grams per prune, 17 to 22 prunes per cup) and bite-size pitted prunes (approximately 5 to 6 grams per prune, 30 or more per cup) pack similarly by cup weight because smaller prunes fill inter-prune air gaps more efficiently while individually contributing less mass. The two forms cluster in the 160-180 g/cup range across major producers, supporting the single-figure publish at USDA's 174 g/cup rather than a range.

Compared to other dried fruits on the site, prunes at 174 g/cup sit in the middle of the milled dried-fruit cluster (dried apricots, dried figs, dried apples, dried pineapple, dried mango) and above the sugar category dried fruits (raisins, dried cranberries, dried blueberries, dried cherries) which cluster around 140-160 g/cup. The site's category boundary places dried fruit larger than raisin size in the milled category, and prunes qualify as milled by both size and physical packing behavior.

Category assignment is milled per the site's established rule that dried fruit larger than raisin size behaves as fibrous plant particulate rather than crystalline particulate. Raisin-sized dried fruits go to sugar; larger dried fruits go to milled.

Confidence is medium reflecting USDA Standard Release direct cup portion (highest sourcing tier) cross-validated against Sunsweet per-prune weight consistency. For baking accuracy, weigh prunes rather than counting them, particularly for recipes calling for 1 cup chopped prunes where knife-cut piece geometry substantially changes cup weight compared to whole pitted prunes. This entry represents a moat play for the site: no other cup-to-gram reference publishes prunes cup weight with the physical explanation of pit-cavity air-void behavior, and no other reference notes the Sunsweet market dominance and cross-format cup-weight convergence transparently.