Cups to Fluid Ounces
Convert cups (cup) to fluid ounces (fl oz). Both measure capacity and volume, and the conversion comes up in cooking, chemistry, fuel work.
The Formula
``
fluid ounces = cups × 8
cups = fluid ounces × 0.125
`
One cup is 8 fluid ounces, and one fluid ounce is 0.125 cups.
Conversion Table
| Cups | Fluid Ounces |
|---|---|
| 1 cup | 8 fl oz |
| 2 cup | 16 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 |
| 500 cup | 4,000 fl oz |
| 1,000 cup | 8,000 fl oz |
The Other Direction
| Fluid Ounces | 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 |
| 25 fl oz | 3.125 cup |
| 50 fl oz | 6.25 cup |
| 100 fl oz | 12.5 cup |
| 500 fl oz | 62.5 cup |
| 1,000 fl oz | 125 cup |
What Each Unit Is
Cups (cup) — the US customary cup: exactly 240 millilitres in nutrition labelling, 236.588 mL legally. An American cooking measure standardised by Fannie Farmer in the 1890s.
Fluid Ounces (fl oz) — the US fluid ounce: exactly 29.5735295625 millilitres. One sixteenth of a US pint, descended from the wine gallon.
A Sense of Scale
A coffee mug holds about 1.5 cups- US recipes measure everything in cups
- A shot is 1.5 fl oz
- A soda can is 12 fl oz
- A US coffee cup is 8 fl oz
Precision
The factor 8 is rounded. For engineering work carry more digits than the table above, and round only at the end — rounding at each step compounds.
Watch Out For
- A US cup is 237 mL, a metric cup 250 mL and a Japanese cup 200 mL. Baking by volume is why the same recipe fails in another country.
- A UK fluid ounce is 28.41 mL — close enough to confuse, far enough to ruin a cocktail.
In Code
`javascript
const cupToFluidOunce = (value) => value * 8;
``
Where This Conversion Comes Up
- Cooking
- Chemistry
- Fuel
- Beverages
- Medicine
How Many Decimals Do You Need?
Rounding the factor costs accuracy, and how much depends on the factor. Converting 137 cup with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 cup becomes | Error |
|---|---|---|---|
| 0 | 8 | 1,096 | — |
| 1 | 8 | 1,096 | — |
| 2 | 8 | 1,096 | — |
| 3 | 8 | 1,096 | — |
| 4 | 8 | 1,096 | — |
The right number of significant figures is set by your input, not by the converter. If you measured cups to three significant figures, the answer in fluid ounces is only good to three — writing more digits claims precision the measurement never had.