Chopped walnuts

One US cup of chopped walnuts weighs 117 grams. Going the other way, 100 grams is about 0.85 cups.

Also called walnut pieces, chopped English walnuts.

Chopped walnuts sit in the milled category not because they are milled but because they pack by scoop the way milled powders and small seeds do. A cup of chopped walnuts is what remains after whole walnut halves are broken into rough pieces of about a quarter-inch, poured into a measuring cup, and lightly leveled. Both King Arthur Baking and USDA FoodData Central publish a figure for this preparation, and the two agree well.

USDA FoodData Central (FDC 170187, Nuts, walnuts, english) gives 117 grams per cup for chopped walnuts, which implies a density of 0.4945 g/mL on the US customary cup of 236.5882365 mL. King Arthur publishes 113 grams for the same measurement, implying 0.4776 g/mL. The gap between the two is 3.5%, comfortably inside the 10% tolerance this site applies to milled and packed-piece ingredients, so both figures are accepted and the USDA figure is published as the site's primary value. Neither source specifies exactly how coarse the chop is, but for the ordinary case of a knife-chopped walnut for baking, both figures are in the plausible range.

The size of the chop matters more than a source can encode. A fine chop, where pieces are closer to an eighth of an inch, packs tighter and can push the cup weight up to about 130 g. A coarse chop with pieces near half an inch traps more air and can drop it to about 105 g. The published figure represents the ordinary case for baking, and a recipe that calls for chopped walnuts should be met by chopping until the pieces roughly match commercial chopped walnut packaging.

This entry is specifically for chopped walnut kernels from the common English walnut (Juglans regia). It does not cover walnut halves, which pack with more air gaps and weigh less per cup; ground walnut meal or walnut flour, which is much finer and packs denser; or black walnuts (Juglans nigra), a distinct species with slightly different fat content and correspondingly different density. Each of those, when sourced, will be a separate entry.

The confidence grade is medium because two independent sources agree within tolerance and both are widely used references, but no third source at a higher tier (a standards body or an independent bench measurement) confirms the figure. High confidence will require a third independent measurement.