Red lentils

One US cup of red lentils weighs 192 grams (6.8 ounces). Going the other way, 100 grams is about 0.52 cups.

Also called split red lentils, red split lentils, pink lentils, masoor dal, dried red lentils, dry red lentils.

Dried beans, lentils and peas compared: cup weights side by side, the source behind each, and why they differ.

A cup of dry red lentils weighs 192 g (6.8 oz). USDA, two America's Test Kitchen recipes and Bob's Red Mill's label agree within 4%, so this entry publishes USDA's figure.

Red lentils are lentils (Lens culinaris) with the seed coat taken off. Under the coat the seed is orange-red, and most red lentils are also split into halves, sold as masoor dal in South Asian shops. Without a coat they cook in 15 to 20 minutes and fall apart into a purée, which is why they go into dal and soup rather than salads. Whole green and brown lentils have their own entry.

USDA SR Legacy "Lentils, pink or red, raw" (FDC 174284) gives 1 cup = 192 g at 7.8% water, the same weight USDA gives whole lentils. That could look like one figure copied across two records, so the independent sources matter here. America's Test Kitchen's Spiced Red Lentils (Masoor Dal) calls for "8 ½ ounces (1 ¼ cups) red lentils", 192.8 g per cup, and its Red Lentil Soup gives 1 1/2 cups as 10 1/2 ounces, 198 g per cup. Bob's Red Mill prints 1/4 cup as 50 g on its 27-ounce bag, with about 15 servings, which works out to 200 g a cup and fits the bag weight. Kroger's red lentils print 35 g per quarter cup, the serving weight that brand prints on all its dry beans, so that label is kept without a figure.

The physical check: hulling and splitting change the shape. Flat half-lenses can lie closer together than whole ones, while their broken edges catch and leave gaps. The measurements say the two roughly cancel: dry red lentils weigh the same per cup as whole green and brown lentils, within a few percent. At a seed density near 1.4 g/mL, the figure measured for whole lentils, 192 g in a 237 mL cup means the lentils fill about 57% of it and air the rest.

Cooked red lentils behave differently from whole ones. They collapse into a dense purée with little air left in it, so a cup weighs far more: Health Canada lists pink lentils, boiled, at 179 g per 175 mL, about 242 g a cup, against 197 g for boiled whole lentils. USDA has no cooked red lentil record, so that single figure is described here but not published as a second state. How much a cup of cooked red lentils weighs also depends on how long they cooked and how much water they kept.

Practical guidance: use 192 g per cup of dry red lentils, 96 g per half cup and 48 g per quarter cup; a pound is about 2 1/3 cups. Rinse them in a sieve until the water runs clearer. For a dal that calls for cooked red lentils by the cup, weigh them dry instead, since the cooked weight depends on how far they have broken down. USA Pulses' rule of thumb, 1/2 cup dry to 1 cup cooked, is a starting point for the volume.