Fluid Ounces to Cups
Convert fluid ounces (fl oz) to cups (cup). Both measure capacity and volume, and the conversion comes up in cooking, chemistry, fuel work.
The Formula
``
cups = fluid ounces × 0.125
fluid ounces = cups × 8
`
One fluid ounce is 0.125 cups, and one cup is 8 fluid ounces.
Conversion Table
| 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 |
The Other Direction
| 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 |
What Each Unit Is
Fluid Ounces (fl oz) — the US fluid ounce: exactly 29.5735295625 millilitres. One sixteenth of a US pint, descended from the wine gallon.
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.
A Sense of Scale
A shot is 1.5 fl oz- A soda can is 12 fl oz
- A US coffee cup is 8 fl oz
- A coffee mug holds about 1.5 cups
- US recipes measure everything in cups
Precision
The factor 0.125 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 UK fluid ounce is 28.41 mL — close enough to confuse, far enough to ruin a cocktail.
- 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.
In Code
`javascript
const fluidOunceToCup = (value) => value * 0.125;
``
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 fl oz with the factor truncated at each decimal place:
| Decimals kept | Factor | 137 fl oz becomes | Error |
|---|---|---|---|
| 0 | 0 | 0 | 100.0000% |
| 1 | 0.1 | 13.7 | 20.0000% |
| 2 | 0.13 | 17.81 | 4.0000% |
| 3 | 0.125 | 17.125 | — |
| 4 | 0.125 | 17.125 | — |
The right number of significant figures is set by your input, not by the converter. If you measured fluid ounces to three significant figures, the answer in cups is only good to three — writing more digits claims precision the measurement never had.