Scallions (green onions)

One US cup of scallions (green onions) weighs 100 grams (3.5 ounces), measured chopped, white and green parts, spooned and leveled. Going the other way, 100 grams is about 1.00 cups.

Fresh herbs and aromatics compared: cup weights side by side, the source behind each, and why they differ.

A cup of chopped scallions, white and green parts together, weighs about 100 g (3.5 oz), and a tablespoon about 6 g: USDA, its school Food Buying Guide and Norway's health directorate agree within 6.1%. Thinly sliced scallions are lighter, 57 to 64 g a cup by the Culinary Institute of America and King Arthur Baking.

Scallions, also called green onions or spring onions, are young onions pulled before the bulb swells: a small white base under long, hollow green leaves. They are sold in bunches and used raw in salads, salsas, dips and as a garnish, and cooked in stir-fries, fried rice, pancakes and soups. Recipes ask for them chopped or thinly sliced, sometimes the white and light green parts only, sometimes the greens only.

USDA's record for scallions, tops and bulb together, weighs a cup chopped at 100 g and a tablespoon at 6 g. USDA's school Food Buying Guide gets 15 quarter-cup servings of raw scallions with tops from each pound as bought, 0.83 lb after trimming, which is 100.4 g a cup, and for the white parts without tops 6.7 quarter cups from 0.37 lb, 100.2 g a cup. Norway's health directorate weighed a decilitre of spring onion at 40 g, 94.6 g a US cup. The three are within 6.1% of each other, inside the 10% this site allows for chopped produce, and this site publishes USDA's 100 g with high confidence.

For thinly sliced scallions the CIA's chart gives 1 cup at 2 oz, 57 g, and a medium scallion as about a quarter cup sliced, 14 g; King Arthur's chart gives 1 cup sliced at 2 1/4 oz, 64 g. The two are 12% apart, just over the tolerance, so the sliced state publishes the range. King Arthur's figure is not wrong: it is one end of that range, and both sources agree that sliced scallions weigh much less by the cup than chopped ones.

The physical check: the white base is solid and cuts into small, dense pieces, while the green leaves are thin-walled hollow tubes. Chopped with the whites, the pieces flatten and pack, and a cup comes to about 0.42 g/mL. Sliced thinly, the green rings stay round, each holding air inside its wall as well as between the rings, so the same cup holds less: 0.24 to 0.27 g/mL. The Food Buying Guide's equal figures for whites alone and for whole scallions show that the white base is not the whole story; how thin the slices are and how loosely they are spooned matter as much.

Practical guidance: use 100 g a cup, 25 g a quarter cup and about 6 g a tablespoon for chopped scallions. For thinly sliced scallions, mostly greens, expect 57 to 64 g a cup, about 3.5 to 4 g a tablespoon. A medium scallion weighs about 15 g by USDA, which is about 2 1/2 tablespoons chopped. For cooking, the difference between the two hardly matters; for a garnish or for scallion pancakes, where they are a main ingredient, weigh them.