Cups to Fluid Ounces
Type a value in either box to convert between cups and fluid ounces. The factor is 8.
| Cups | Fluid Ounces |
|---|---|
| 1 cup | 8 fl oz |
| 2 cup | 16 fl oz |
| 3 cup | 24 fl oz |
| 5 cup | 40 fl oz |
| 10 cup | 80 fl oz |
| 25 cup | 200 fl oz |
| 50 cup | 400 fl oz |
| 100 cup | 800 fl oz |
How to use
- Enter a value in the Cups field.
- The Fluid Ounces figure appears immediately — no button to press.
- Typing in the Fluid Ounces field converts back to Cups the same way.
- Use the reference table for the values that come up most often.
Cups to Fluid Ounces formula
Converting cups to fluid ounces is a single multiplication by 8.
fl oz = cup × 8
Put another way, one cup is exactly 8 fluid ounces.
Why this factor: the cup and the fluid ounce are both defined against the liter, so dividing one definition by the other gives 8 directly. Both definitions are set out in full below.
To go the other way, divide by 8 — or use the Fluid Ounces to Cups converter, which is the same calculation reversed.
Worked example
Start with 2 cup. Multiply by 8 to get 16 fl oz.
2 cup × 8 = 16 fl oz
The converter above does this for any value you type, in either direction.
What is a cup?
A US customary cup is the standard cooking volume measure in American recipes.
Definition: Exactly one sixteenth of a US liquid gallon, so exactly 236.5882365 milliliters.
Where it is used: American recipes and baking, where dry and liquid ingredients alike are measured by cup.
Worth knowing: Nutrition labels use the US *legal* cup of exactly 240 mL, and a metric cup is 250 mL — three slightly different cups are in circulation.
What is a fluid ounce?
A US fluid ounce is a small liquid volume, one eighth of a cup.
Definition: Exactly one 128th of a US liquid gallon, so exactly 29.5735295625 milliliters.
Where it is used: Beverage cans and bottles, cosmetics, and small liquid quantities in the US.
Worth knowing: Measures volume, not weight — a fluid ounce of water weighs about 1.04 avoirdupois ounces. The imperial fluid ounce is 28.41 mL.
Cups vs Fluid Ounces
The cup and the fluid ounce belong to the same family of units, so converting between them is usually a matter of shifting a decimal point or applying a small whole-number factor.
Frequently asked questions
How many fluid ounces are in a cup?
One cup equals 8 fluid ounces.
What is the formula to convert cups to fluid ounces?
Multiply the number of cups by 8. To reverse it, divide by 8 instead.
How do I convert fluid ounces back to cups?
Divide by 8, which is the same as multiplying by 0.125.
How many fluid ounces are in 10 cups?
10 cup works out to 80 fl oz.
Is there anything to watch out for with cups?
Nutrition labels use the US *legal* cup of exactly 240 mL, and a metric cup is 250 mL — three slightly different cups are in circulation.
How is the cup defined?
Exactly one sixteenth of a US liquid gallon, so exactly 236.5882365 milliliters.