There are 8 ounces in a cup. A cup is a unit of measurement for volume, and it is equal to 8 fluid ounces. This means that there are 8 ounces of liquid in a cup-sized container. One cup is also equivalent to 1/16 of a gallon or 1/4 of a quart, so you can use these conversions to determine the number of ounces in a given amount of liquid. For example, if you have 1 quart of liquid, you can multiply 1 by the conversion factor of 4 to determine that you have 4 cups, or 32 ounces, of liquid.