Potatoes Measurements and Conversions

Recipes list potatoes in three ways: by count, by weight, or by cups of diced or shredded potato. Count is the least exact, because a "medium" potato covers a wide range of sizes. Weight is the most exact, and cups sit in between.

The cup weight on this page is USDA's figure for raw potato diced with the skin on. USDA gives it for half a cup, and this site doubles it for the full cup. Peeled potatoes, big chunks and shredded potatoes all fill a cup a little differently, so treat the number as a guide.

Pour the dice into a dry measuring cup and shake it gently to settle them, without pressing. When a recipe gives a weight, check whether it means whole or peeled potatoes, and weigh at that stage.

If you hold cut potatoes in cold water to stop them browning, drain them well before measuring. Water left in the cup adds weight and makes the dice look like more than they are.

USDA sorts whole potatoes by diameter. A small potato is about 1 3/4 to 2 1/2 inches across, a medium one 2 1/4 to 3 1/4 inches, and a large one 3 to 4 1/4 inches. The ranges overlap, so a potato near the line could fall in either class.

The by-the-piece table above turns each size into weight and cups of dice. A large potato gives about 2 1/2 cups diced, enough for a small sheet pan of roasted potatoes.

Store names such as "baking" or "new" potatoes do not follow these size classes. Weigh them when a recipe depends on the amount.

USDA's cup of mashed potatoes, made with whole milk, weighs about 40 percent more than a cup of raw dice, as the table of other kinds above shows. Mashing fills in the gaps between pieces, and the milk adds weight of its own.

Cooked diced potatoes are not in this data. Boiling and roasting change the water in a potato, so weigh potatoes raw whenever a recipe lets you.

When a recipe lists cups of mashed potatoes, such as a topping for shepherd's pie, measure the finished mash itself rather than converting from raw potatoes.