Cups to fluid ounces converter

Cups and fluid ounces both measure volume, so this swap is exact and does not depend on the ingredient. The tool above converts cups, fluid ounces, tablespoons, milliliters, pints, and more. One thing to keep straight: a fluid ounce measures space, not weight.

Pick units or type in either box.

Common cup and fluid ounce conversions

Volume only. These hold for any liquid or dry ingredient:

  • 1 cup = 8 fluid ounces
  • 3/4 cup = 6 fluid ounces
  • 2/3 cup = about 5.3 fluid ounces
  • 1/2 cup = 4 fluid ounces
  • 1/3 cup = about 2.7 fluid ounces
  • 1/4 cup = 2 fluid ounces
  • 1 fluid ounce = 2 tablespoons
  • 1 fluid ounce = 6 teaspoons
  • 1 fluid ounce = about 30 milliliters
  • 2 cups = 16 fluid ounces = 1 pint
  • 4 cups = 32 fluid ounces = 1 quart

How the tool works

A US cup is 8 US fluid ounces by definition. A fluid ounce is 29.57 milliliters. The tool converts your input to milliliters, then to the unit you want, so any pair works.

Because both units measure volume, the conversion is the same whether you are measuring water, oil, flour, or sugar. The number of fluid ounces in a cup never changes.

Fluid ounces vs weight ounces

This is the conversion people get wrong most often. A fluid ounce measures volume, the space something takes up. A weight ounce, often just called an ounce, measures mass, how heavy something is. They share a name but they are not the same thing.

One US fluid ounce of water happens to weigh almost exactly one weight ounce, which is where the confusion starts. For flour, honey, or oil, a fluid ounce and a weight ounce are different numbers. If a recipe lists ounces for a dry ingredient, it usually means weight, so weigh it.

UK fluid ounces are slightly smaller than US fluid ounces, about 28.4 ml versus 29.57 ml. A UK pint is 20 fluid ounces, not 16.

US vs UK fluid ounces

A US fluid ounce is 29.5735 milliliters. A UK imperial fluid ounce is 28.4131 milliliters. The bigger gap is the pint: a US pint is 16 fluid ounces, a UK pint is 20. If a recipe is British and lists pints or fluid ounces, the amounts run larger than US ones.

Common cup and fluid ounce mistakes

  • Treating fluid ounces as weight. 8 fluid ounces of flour does not weigh 8 ounces. For dry ingredients by weight, use the cups to grams tool.
  • Using a UK fluid ounce for a US recipe, or the reverse. They differ by about 4 percent, and the pint differs by 25 percent.
  • Measuring liquids in a dry measuring cup. A liquid measuring cup with a spout and a gap at the top is more accurate for fluid ounces.
  • Assuming a coffee mug holds 8 fluid ounces. A standard measuring cup is 8 fluid ounces; a mug is often 10 to 12.

FAQ

How many fluid ounces are in a cup?
1 US cup is 8 US fluid ounces. So 1/2 cup is 4 fluid ounces and 1/4 cup is 2 fluid ounces.
Is 1 cup the same as 8 ounces?
1 cup is 8 fluid ounces, which measure volume. It is only 8 weight ounces if you are measuring water, by coincidence. For other ingredients the weight is different.
How many fluid ounces are in 2 cups?
2 US cups are 16 fluid ounces, which is also 1 US pint.
What is a fluid ounce in tablespoons?
1 fluid ounce is 2 tablespoons, or 6 teaspoons.
Are US and UK fluid ounces the same?
No. A US fluid ounce is 29.57 ml; a UK fluid ounce is 28.41 ml. And a US pint is 16 fluid ounces while a UK pint is 20.

Related tools and guides

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Where these numbers come from

US volume units are defined by NIST. A US cup is exactly 236.5882365 milliliters and contains exactly 8 US fluid ounces. One US fluid ounce is 1/128 of a US gallon, 29.5735295625 milliliters.

Sources

Our numbers and methodology cross-reference these authorities:

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