Corn flakes

One US cup of corn flakes weighs 28 grams (0.99 ounces). Going the other way, 100 grams is about 3.57 cups.

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

A cup of corn flakes weighs about 28 g (1 oz). USDA, America's Test Kitchen and Kellogg's own label agree within 1.3%, and a cup of crushed flakes is a different measure, covered below.

Corn flakes are toasted flakes of milled corn, sweetened lightly with sugar and malt and flattened between rollers, sold by Kellogg's since the early twentieth century and by every store brand. Besides breakfast, they are a baking and cooking ingredient: crushed for oven-fried and air-fried chicken and fish, in cornflake cookies and wreaths, in cornflake-topped casseroles and funeral potatoes, and in no-bake clusters and bars.

USDA's record for Kellogg's Corn Flakes weighs a cup at 28 g, the cereal's standard one-cup serving. America's Test Kitchen's air fryer chicken uses 2 cups, 2 oz, of flakes before crushing, 28.35 g a cup. Kellogg's label gives a serving of 1 1/2 cups as 42 g, again 28 g a cup. The three are within 1.3%, well inside the 10% this site allows for cereals and other milled ingredients, so this site publishes 28 g with high confidence.

Most recipes measure corn flakes whole and crush them afterwards, as Test Kitchen does, and that is the measure this page gives. A cup of flakes crushed first and then measured is much heavier, because crushing removes most of the air: Kellogg's own muffin recipe calls for 4 cups of Corn Flakes or 1 cup of its ready-made Corn Flake Crumbs.

King Arthur Baking's chart has no corn flakes row.

The physical check: corn flakes are thin, curled, crisp sheets, and a cup of them is nearly all air: 28 g a cup is about 0.12 g per millilitre, an eighth of the weight of the same cup of water, which is what thin, stiff flakes leaning on each other leave. Puffed rice cereal is about as light, 28 g a cup on this site; dense cereals such as bran sticks and Grape-Nuts weigh two to four times as much per cup. Because so much of the cup is air, the way the flakes fall changes the weight more than with denser ingredients, and broken flakes from the bottom of the box pack heavier than whole ones.

Practical guidance: use 28 g per cup of whole corn flakes, about 1.7 g per tablespoon of flakes. When a recipe gives cups of crushed flakes, start from about four times that volume of whole flakes, as Kellogg's does, or better, weigh. Test Kitchen's coating for air-fried chicken is 2 cups of whole flakes, 56 g, crushed. An 18 oz box holds about 18 cups of flakes.