How Many Ounces in a Cup?

1 cup = 8 fluid ounces

There are exactly 8 fluid ounces in one US cup.

How to Convert Cups to Fluid Ounces

To convert cups to fluid ounces, multiply by 8.

For example: 5 cups × 8 = 40 fluid ounces.

Why This Number Matters

This is the most searched cooking conversion in the United States, because American recipes use cups while bottles, cans and nutrition labels use fluid ounces. Scaling a recipe up or down runs through it every time.

A 16-ounce bottle of water is exactly 2 cups, which is handy when a recipe calls for 2 cups of liquid.

What People Get Wrong

This only holds for fluid ounces, which measure volume. A cup of a dry ingredient does not weigh 8 ounces: a cup of all-purpose flour weighs about 4.25 ounces, and a cup of brown sugar about 7.5 ounces packed.

Cups to Fluid Ounces Conversion Table

How many fluid ounces are in each number of cups.
Cups (cup)	Fluid ounces (fl oz)
1	8
2	16
3	24
4	32
5	40
6	48
7	56
8	64
9	72
10	80
11	88
12	96
13	104
14	112
15	120
16	128
17	136
18	144
19	152
20	160
25	200
30	240
40	320
50	400
75	600
100	800
250	2,000
500	4,000
1,000	8,000

About These Units

The cup

A US customary cup is 8 fluid ounces, or exactly 236.5882365 milliliters. Nutrition labels use a separate "legal cup" of exactly 240 milliliters, and a metric cup is 250 milliliters.

The fluid ounce

A US fluid ounce is exactly 29.5735295625 milliliters and measures volume, not weight. The UK imperial fluid ounce is slightly smaller at 28.41 milliliters.

Definitions follow NIST Handbook 44, Appendix C. See how we calculate for the exact values and rounding rules.

Frequently Asked Questions

How many ounces in half a cup?

Half a US cup is 4 fluid ounces.

Is a cup of flour 8 ounces?

No. A cup is 8 fluid ounces of volume, but a cup of all-purpose flour weighs only about 4.25 ounces. Dry ingredients should be weighed, not converted from volume.