Grape juice

One US cup of grape juice weighs 253 grams (8.9 ounces). Going the other way, 100 grams is about 0.40 cups.

Also called 100% grape juice, Concord grape juice, purple grape juice, white grape juice, unsweetened grape juice.

Fruit juices compared: cup weights side by side, the source behind each, and why they differ.

A cup of grape juice weighs 253 g (8.9 oz), a density of 1.07 g/mL. USDA weighs a cup of bottled unsweetened grape juice at 253 g and Health Canada's 125 mL at 132 g, 250 g per cup, within 1.3%. It is one of the heaviest fruit juices because grapes are among the sweetest fruits.

Most grape juice sold in the US is made from Concord grapes, the dark purple American variety, either pressed or reconstituted from concentrate; white grape juice is made from green grapes such as Niagara. Both are sold as 100% juice with no added sugar, and the sweetness is the grape's own. USDA's composition data give 14.2 g of sugars per 100 g of juice, against 9.6 g for apple juice.

USDA's Standard Reference record (FDC 173042) gives 1 cup as 253 g and 1 fl oz as 31.6 g, both 1.069 g/mL. Health Canada's Nutrient Value of Some Common Foods weighs 125 mL of ready-to-drink grape juice at 132 g, 1.056 g/mL; with whole-gram rounding on 125 mL it could be anywhere from 1.052 to 1.060. The two agree within this site's 5% tolerance for liquids, and USDA's figure, from the larger measure, is published.

The physical check: the FDA sets the minimum strength of 100% grape juice at 16.0 °Brix, and a sugar solution of that strength weighs 1.062 g/mL by the USDA sucrose table, 251 g per cup. Measurements of wine-grape juice show the same rule from both sides: Cabernet Sauvignon juice weighed 1.040 g/mL at 13.6 °Brix and 1.076 g/mL at 21 °Brix. Retail grape juice, at about 16 °Brix, sits between them at 1.06 to 1.07 g/mL.

Concord and white grape juice are not measured separately by USDA, and their sugar content is close enough that they weigh the same per cup within the tolerance. Grape juice cocktails and grape drinks, which add water and sugar, are different products and are not covered here.

How a cup is measured matters little for a juice. A liquid fills a measuring cup completely, with no air between particles, so two careful cooks get the same weight, and the only variation is in the juice itself. The FDA sets a minimum strength rather than a fixed one, and retail juices sit somewhat above it, but that difference moves the cup weight by only a few grams.

Practical guidance: use 253 g per cup, 127 g per half cup, 63 g per quarter cup and 15.8 g per tablespoon. A 64 fl oz bottle holds 8 cups, about 2.02 kg. For jelly, where the juice's weight matters for the sugar and pectin ratio, 4 cups of grape juice weigh about 1,010 g.