How to Convert US fluid ounces to US cups (fl oz to cup)
Volume conversions help with baking from American recipes, comparing petrol prices quoted per gallon abroad with pump prices per litre here, and reading PUB water bills in cubic metres. This guide shows how to convert us fluid ounces into us cups by hand, with examples and a quick-reference table.
The conversion
To convert us fluid ounces to us cups, multiply the value by 0.125. To go the other way, divide by the same number (or multiply by 8). For a quick estimate, multiply by about 0.12.
US cups = us fluid ounces × 0.125
Worked examples
- 3 fl oz = 0.375 cup
- 12.5 fl oz = 1.5625 cup
- 75 fl oz = 9.375 cup
US fluid ounces to US cups table
| US fluid ounces | US cups |
|---|---|
| 1 fl oz | 0.125 cup |
| 2 fl oz | 0.25 cup |
| 5 fl oz | 0.625 cup |
| 10 fl oz | 1.25 cup |
| 20 fl oz | 2.5 cup |
| 25 fl oz | 3.125 cup |
| 50 fl oz | 6.25 cup |
| 100 fl oz | 12.5 cup |
| 250 fl oz | 31.25 cup |
| 500 fl oz | 62.5 cup |
| 1,000 fl oz | 125 cup |
Common questions
Is fl oz to cup exact?
The factors used here are the internationally defined values where they exist; results are rounded for display only.
How do I convert back?
Use the US cups to US fluid ounces converter.
Mistakes to avoid
Forgetting squared and cubed units
Area and volume factors are the length factor squared or cubed, so 1 m² is about 10.76 sq ft, not 3.28.
Rounding the factor too early
Using 3 instead of 3.28 for feet per metre introduces an error of almost 9% before you have started.
Multiplying when you should divide
Converting to a smaller unit gives a bigger number, and converting to a larger unit gives a smaller one. If your answer moves the wrong way, you have inverted the factor.
Background
For everyday use, three or four significant figures are usually enough. Engineering, science and trade documents may need more, and rounding should happen only at the end of a calculation.
A conversion table is handy for common values, but a calculator is faster and avoids interpolation errors for anything in between.
Writing the units next to every number while you work is the simplest way to avoid mistakes. If the units do not cancel to leave the one you want, the calculation is set up wrongly.
For any value, use the US fluid ounces to US cups Converter or browse all volume converters.
Run your own numbers: US fluid ounces to US cups Converter