How many Cups of Confectioner Sugar in a 1 lb box?

A 1-pound box of powdered (confectioner’s) sugar typically contains about 3 3/4 cups.

This is based on the general measurement that 1 cup of powdered sugar weighs about 4 ounces, and there are 16 ounces in a pound. So:

\frac{16 \, \text{ounces}}{4 \, \text{ounces per cup}} = 4 \, \text{cups}.

However, powdered sugar is often sifted when measured, so the actual measurement may be slightly less if you are measuring without sifting.