How to convert cups to fl oz?
Type a value in either box, and the answer shows it in the other unit as you type.
- Fluid ounces (fl oz)
- 8
1 cup = 8 fl oz.
Fluid ounces (fl oz): 8. 1 cup = 8 fl oz.
Fluid ounces (fl oz) by cups (cup)
How to calculate
Converts cups (cup) to fluid ounces (fl oz) and back, with the exact unit definitions.
Example with the default inputs (Cups (cup) 1): 1 cup = 8 fl oz.
Formula: fl oz = cup × 8
- 1 cup = 8 fluid ounces, from the exact definitions in NIST SP 811.
- Cups, ounces, tablespoons, teaspoons, pints, quarts, and gallons are US customary units: 1 US cup is 8 US fluid ounces.
- Ounces here are US fluid ounces, a volume. An ounce of weight (1/16 lb) is a different unit.
- The answer shows at most 6 decimal places; the calculation keeps full precision.
Worked examples
Each example is checked against the calculator on every build.
- Cups (cup) 1 gives Fluid ounces (fl oz) 8.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
- Cups (cup) 2.5 gives Fluid ounces (fl oz) 20.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
- Fluid ounces (fl oz) 20 gives Cups (cup) 2.5.Source: Exact unit definitions in NIST SP 811 (2008), Appendix B.8
Other questions people ask
How many fluid ounces are in a cup?
1 cup is 8 fluid ounces, from the exact unit definitions (NIST SP 811).
How do I convert cups to fl oz?
Multiply by 8: fl oz = cup × 8. For example, 1 cup × 8 = 8 fl oz.
How do I convert fl oz back to cups?
Multiply by 0.125, or type the fluid ounces into the second box and the converter works it out. 1 fluid ounce is 0.125 cups.
Is an ounce here a weight or a volume?
A volume: the US fluid ounce, 1/8 of a US cup (29.57 mL). An ounce of weight (1/16 lb, 28.35 g) only matches a fluid ounce for water and liquids like it.