Cups to Fluid Ounces Converter

About the cup to fl oz calculation

One cup is exactly 8 fluid ounces, so converting between them is a single multiplication. Enter any value above and the result updates as you type. The US legal cup is 240 ml; the customary cup used in recipes is 236.6 ml. The US fluid ounce. Measures volume, not weight — quite separate from the ounce.

Formula

fl oz = cup × 8

1 cup = 8 fl oz
1 fl oz = 0.125 cup

Worked example

To convert 1 cup, multiply by 8: 1 × 8 = 8 fl oz.

Frequently asked questions

How many fluid ounces are in a cup?

There are 8 fluid ounces in one cup. To convert any amount, multiply the number of cups by 8.

How do I convert fluid ounces back to cups?

Divide instead of multiplying, or equivalently multiply by 0.125. One fluid ounce is 0.125 cups.

Is this conversion exact?

Yes. Since the international agreement of 1959, the relationship between cups and fluid ounces is defined exactly rather than measured, so the only rounding here is in how many decimal places we show.

Where is each of these units used?

Cups: the US legal cup is 240 ml; the customary cup used in recipes is 236.6 ml. Fluid Ounces: the US fluid ounce. Measures volume, not weight — quite separate from the ounce.

Sources

• NIST Special Publication 811 — Guide for the Use of the International System of Units