Fluid Ounces to Cups
Convert fluid ounces to cups instantly — one fluid ounce is 0.125 cups.
| Fluid Ounces | Cups |
|---|---|
| 1 fl oz | 0.125 cup |
| 2 fl oz | 0.25 cup |
| 3 fl oz | 0.375 cup |
| 5 fl oz | 0.625 cup |
| 10 fl oz | 1.25 cup |
| 25 fl oz | 3.125 cup |
| 50 fl oz | 6.25 cup |
| 100 fl oz | 12.5 cup |
How to use
- Enter a value in the Fluid Ounces field.
- The Cups figure appears immediately — no button to press.
- Typing in the Cups field converts back to Fluid Ounces the same way.
- Use the reference table for the values that come up most often.
Fluid Ounces to Cups formula
To convert fluid ounces to cups, multiply by 0.125.
cup = fl oz × 0.125
Put another way, one fluid ounce is exactly 1/8 of a cup.
Why this factor: the fluid ounce and the cup are both defined against the liter, so dividing one definition by the other gives 0.125 directly. Both definitions are set out in full below.
To go the other way, divide by 0.125 — or use the Cups to Fluid Ounces converter, which is the same calculation reversed.
Worked example
Start with 2 fl oz. Multiply by 0.125 to get 0.25 cup.
2 fl oz × 0.125 = 0.25 cup
The converter above does this for any value you type, in either direction.
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.
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.
Fluid Ounces vs Cups
The fluid ounce and the cup 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 cups are in a fluid ounce?
One fluid ounce equals 0.125 cups.
What is the formula to convert fluid ounces to cups?
Multiply the number of fluid ounces by 0.125. To reverse it, divide by 0.125 instead.
How do I convert cups back to fluid ounces?
Divide by 0.125, which is the same as multiplying by 8.
How many cups are in 10 fluid ounces?
10 fl oz works out to 1.25 cup.
Is there anything to watch out for with fluid ounces?
Measures volume, not weight — a fluid ounce of water weighs about 1.04 avoirdupois ounces. The imperial fluid ounce is 28.41 mL.
How is the fluid ounce defined?
Exactly one 128th of a US liquid gallon, so exactly 29.5735295625 milliliters.