Chopped vegetables grams per cup: onion, leek, carrot, pepper, mushroom, olive

A US cup of chopped or sliced vegetables weighs from under 100 grams for sliced mushrooms and diced leeks to about 170 grams for chopped onion. The shape of the pieces and how they pack decide it more than the vegetable does, which is why the same vegetable can vary by a third depending on the knife.

All weights are for a US cup of 236.5882365 ml; a tablespoon is a sixteenth of it. A range means the sources disagree by more than this site’s tolerance for that kind of ingredient, so no single figure is chosen. King Arthur’s figure is shown where this site records one, with the verdict on it. Each ingredient’s own page has every source and the full reasoning.

Vegetables are mostly water, from 76 percent for sweet corn to 95 percent for celery, so the pieces themselves weigh about as much as the same volume of water. What a cup of them weighs depends on how much air is left between the pieces, and that depends on their shape.

Carrots cut into true cubes and bell peppers into flat squares from a thin wall; both pack tightly, and the sources agree closely. Diced bell pepper weighs 149 grams per cup in USDA's measurement, with the Culinary Institute of America at 147 and King Arthur at 142, all within 5 percent. Diced carrots weigh 142 grams per cup by the Culinary Institute, USDA's school Food Buying Guide and King Arthur alike; only USDA's own chopped carrot, at 128 grams, holds that entry to a range.

Onion and celery do not cut into cubes. Onion falls apart into curved layers and celery into arcs, both trap air unevenly, and the sources spread widely: 113 to 172 grams for diced onion and 101 to 142 grams for diced celery. Leeks go further still: a leek is a roll of thin sheaths, so its dice separate into loose flakes, and a cup weighs 89 grams in USDA's measurement, with King Arthur at 92. The size of the dice and how hard the cup is pressed decide where a cook lands.

Slices sit at both ends of the scale. Sliced black olives are flat rings of even thickness that stack like coins, so a cup of drained slices weighs 128 to 142 grams, as much as diced carrot. Sliced mushrooms are the opposite: each slice is a T of cap and stem that props the others up, and a cup weighs 57 to 98 grams depending on the slice, with USDA at 70 grams for slices cut at home.

Shreds are measured on their own terms. Grated carrot weighs 99 to 130 grams per cup depending on the grater and how firmly it is packed, against 128 to 142 grams for the same carrot diced: fine shreds trap more air than small cubes.

Corn kernels are firm and rounded. Frozen kernels measured straight from the bag weigh 136 grams per cup in USDA's measurement, fresh kernels cut from the cob 145 grams, and thawed frozen kernels about 163 grams, because hard frozen kernels do not settle the way moist ones do. King Arthur's 152 grams, given for fresh or frozen corn, matches fresh kernels.

King Arthur gives the same 5 ounces, 142 grams, for diced onions, celery, carrots and bell peppers and for sliced olives. That round figure agrees with the measured data for carrots and peppers and sits inside the ranges for onion, celery and olives, at the top of the olive range. Its separate figures for diced leeks (92 grams) and sliced mushrooms (78 grams) agree with USDA. None of them is rejected.