How many ounces in a cup (cup to fl oz)

One US cup is exactly 8 US fluid ounces. That ratio belongs to the customary system itself and is much older than any link to metric: the 1959 international yard and pound agreement later fixed the yard and the pound against the meter and the kilogram, but it left the ratios between customary units (feet to the yard, ounces to the pound, cups to the gallon) exactly as they were.

Worked through: 0.75 cup x 8 = 6 fl oz.

Going the other way, one US fluid ounce is 0.125 US cups.

For mental arithmetic: Multiply by 8.

The most asked kitchen conversion there is, and the answer depends on which ounce. A US cup is exactly 8 US fluid ounces, which is why the question has a clean answer at all: the cup was defined that way. But a fluid ounce is a volume and a dry ounce is a weight, and recipes use both words. Eight fluid ounces of water weighs about 8.3 ounces, eight fluid ounces of flour weighs about 4.5, and a recipe asking for '8 oz of flour' means the weight. If the ingredient is dry and the recipe is any good, it wants a scale.

Precision is worth matching to the input. A measurement given as 0.25 cup carries one or two significant figures, and reporting its conversion to six implies a precision the original never had.