Enter US cups to find the matching US fluid ounces, including a reduced fraction for recipe amounts like 1/3 or 1 1/2 cups.
This is a volume result, not an ingredient weight.
This exact form can be easier to use when the decimal repeats.
This converter uses US customary cups. Metric, US legal, Imperial, and coffee-maker cups can have different volumes.
Table of contents
How to use our Cups to Fluid Ounces Converter
- Enter the amount from your US recipe, measuring cup, worksheet, or package instruction in "Amount in US cups."
- Use a whole number, decimal, fraction, or mixed number, such as 2, 0.5, 1/3, or 1 1/2.
- Click "Calculate" to see US fluid ounces first, followed by the reduced fraction, tablespoons, and teaspoons.
- Check the result against a familiar amount: 1 US cup equals 8 fl oz, so 1/2 cup equals 4 fl oz.
Definitions
US customary cup: A US volume measure used in many recipes. This converter uses 1 US cup = 8 US fluid ounces.
Fluid ounce (fl oz): A unit of volume, not an ounce used to measure ingredient weight.
Mixed number: A whole number plus a fraction, such as 1 1/2.
Reduced fraction: A fraction with no common factor left in its top and bottom numbers, such as 2/3 instead of 4/6.
Tablespoon (tbsp): A US volume measure equal to 1/2 fluid ounce.
Teaspoon (tsp): A US volume measure equal to 1/6 fluid ounce.
Common mistakes and quick fixes
Mistake: Entering ounces by weight instead of a liquid volume.
Fix: Use this converter only for US cups and US fluid ounces. Ingredient weight needs the ingredient name and a separate weight conversion.
Mistake: Typing a malformed fraction such as 1//2.
Fix: Use one slash only, such as 1/2, or enter a mixed number such as 1 1/2.
Mistake: Using 1/0 as a fraction.
Fix: Enter a number greater than 0 after the slash, such as 1/2 or 3/4.
Mistake: Entering a negative amount.
Fix: Enter 0 cups or a positive amount because a recipe volume cannot be negative.
Mistake: Treating a metric or Imperial cup as a US customary cup.
Fix: Confirm that the source uses US cups before converting because other cup standards have different volumes.
Limitations & Key Assumptions / Boundary Conditions
- The calculation uses US customary cups and US fluid ounces only; it does not convert metric cups, US legal cups, Imperial cups, or coffee-maker cup markings.
- Fluid ounces measure volume, not weight, so a fluid-ounce result cannot determine an ingredient's weight without ingredient-specific information.
- The reduced fraction is exact for accepted finite decimals, simple fractions, and mixed numbers; the decimal form can repeat for entries such as 1/3 cup.
- Negative amounts, zero-denominator fractions, ranges, formulas, and malformed entries are not accepted.
Methodology
Conversion method
The converter treats the entry as a US customary volume. One US cup contains 8 US fluid ounces.
fluid ounces = US cups × 8
It calculates tablespoons and teaspoons from the unrounded fluid-ounce amount.
tablespoons = fluid ounces × 2
teaspoons = fluid ounces × 6
Fractions and decimals
Whole numbers, finite decimals, simple fractions, and mixed numbers are retained as fractions when possible. The calculator multiplies the fraction by 8 and reduces it, so it does not try to create a fraction from a rounded decimal.
For example, 1/3 cup multiplied by 8 equals 8/3 fl oz, shown as 2 2/3 fl oz. That same amount equals 5 1/3 tbsp and 16 tsp.