Butter

One US cup of butter weighs 227 grams (8 ounces). Going the other way, 100 grams is about 0.44 cups.

Also called salted butter, unsalted butter, sweet cream butter, stick of butter, sticks of butter.

A cup of butter weighs 227 g (8 oz), two US sticks of 113 g. USDA, King Arthur and the Land O'Lakes package agree within half a percent, and salted and unsalted butter weigh the same. It is the one cup figure in baking that is set by the package rather than by how the cup is filled.

US butter is sold in 1-pound boxes of four sticks, each stick a quarter pound (4 oz, 113 g) and marked on its wrapper as 1/2 cup and 8 tablespoons. A pound is therefore 2 cups and 32 tablespoons, which is exactly how Land O'Lakes labels it: a serving of 1 tablespoon (14 g), 32 servings to the pound. A recipe that asks for a cup of butter is asking for two sticks cut along the wrapper, not for butter pressed into a measuring cup.

USDA's Standard Reference record for salted butter (FDC 173410) gives 1 cup as 227 g and 1 stick as 113 g, and its unsalted butter record (FDC 173430) gives the same 227 g, so one entry covers both. King Arthur's ingredient weight chart lists 8 tablespoons (1/2 cup) as 113 g, 226 g per cup. The three agree within 0.5%.

The physical check: butter is about 80% milk fat and 16% water, with a little milk protein and salt. Milk fat weighs a little over 0.9 g/mL and water 1.0, so a solid block of butter should weigh about 0.95 g/mL, and 227 g in a 236.6 mL cup is 0.96 g/mL. That is why the 227 g that King Arthur wrongly prints for a cup of milk is right for butter: milk is mostly water and weighs more than water, while butter is mostly fat and weighs less.

Some butter does not follow the stick. Whipped butter has air beaten into it, and USDA weighs a cup at 151 g (FDC 173411), about a third lighter, so it cannot replace stick butter cup for cup. European-style and imported butters are usually sold in 250 g or 8 oz blocks without cup markings, so weigh them. USDA also lists a pat of butter, a 1-inch square a third of an inch high, at 5 g.

Practical guidance: use 227 g per cup, 113 g per half cup or stick, 57 g per quarter cup and 14 g per tablespoon. A 250 g block is about 1 1/10 US cups. Butter in marked sticks needs no scale; butter from a tub or block measures most accurately by weight.