Sliced Mushrooms

One US cup of sliced mushrooms weighs between 57 and 98 grams (2 to 3.5 ounces), depending on how the cup is filled and which source measured it. Use 70 grams (2.5 ounces) for raw mushrooms sliced at home. Every figure behind it is below, with the method each source used.

Also called sliced white mushrooms, sliced button mushrooms, mushroom slices, raw sliced mushrooms, fresh sliced mushrooms, mushroom pieces.

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

A cup of sliced raw mushrooms weighs 57 to 98 g (2 to 3.5 oz). USDA weighs a cup of pieces or slices at 70 g, King Arthur gives 78 g, the Culinary Institute of America about 57 g, and USDA's school Food Buying Guide about 98 g for pre-sliced mushrooms. The gap is far over the 10% tolerance, so this entry publishes the range. For mushrooms sliced at home and dropped loosely into the cup, 70 g is the figure to use.

White button mushrooms (Agaricus bisporus) are the common supermarket mushroom; cremini and portobello are brown strains of the same species. They are about 92% water with very little fat or sugar, so the flesh itself weighs close to water. What changes the cup is shape. A mushroom sliced top to bottom gives thin slices shaped like a T, cap and stem, and those slices cannot lie flat against each other. They cross, prop each other up and leave large gaps, which makes sliced mushrooms the airiest cut in the chopped-vegetable family.

USDA SR Legacy "Mushrooms, white, raw" (FDC 169251) lists 1 cup of pieces or slices at 70 g, half a cup of pieces at 35 g, a cup of whole mushrooms at 96 g and one slice at 6 g. King Arthur gives 1 cup sliced at 2 3/4 oz, 78 g. The Culinary Institute of America's conversion chart gives about 2 oz, 57 g, for a cup sliced, and one large white mushroom as about a quarter cup of slices. USDA's Food Buying Guide for school kitchens counts 18.50 quarter-cup servings in a pound of ready-to-use fresh slices, about 4 5/8 cups per pound, which works out to about 98 g per cup.

The physical check: flesh that is 92% water weighs about 1 g per millilitre, so 70 g in a 237 mL cup means the slices fill under a third of it and air fills the rest. USDA's cup of whole mushrooms, 96 g, holds more mushroom than its cup of slices, so slicing adds air rather than removing it. The Food Buying Guide's higher figure fits machine-cut slices: they are thin and even, and they settle in layers in a measuring scoop, where hand-cut slices are thicker and land at random.

King Arthur's 78 g sits between USDA and the Culinary Institute, inside the range, so it is accepted, not corrected.

Retail labels for fresh sliced mushrooms do not help. Publix and others print 2/3 cup as 85 g, and 85 g is the reference serving for vegetables, so the grams come from the regulation rather than from a weighed cup. Canned slices are a different product: Health Canada weighs 125 mL of drained canned pieces at 82 g, about 155 g per cup, because cooked slices go limp and pack. Its 57 g per 125 mL for stir-fried sliced mushrooms shows the same collapse in the pan.

Practical guidance: use 70 g per cup for raw mushrooms sliced at home, 35 g per half cup and about 4 to 5 g per tablespoon. An 8 oz (227 g) pack of sliced mushrooms is about 3 cups at 70 to 78 g per cup. For dishes where the amount matters, such as duxelles or a cream of mushroom soup, weigh the mushrooms whole before slicing: 96 g of whole mushrooms, one cup whole, gives about 1 1/3 cups of slices.