How many ounces in a cup

How many ounces in a cup

A US cup is 8 fl oz, exactly: NIST Handbook 44 defines the measuring cup as 8 fluid ounces and half a liquid pint, so 8 fluid ounces equals 1 cup. To convert, multiply the cups by 8: ½ cup is 4 fl oz, 2 cups are 16 fl oz and 4 cups, a quart, are 32 fl oz.

Those are fluid ounces, a measure of volume. They hold for anything poured into a liquid measuring cup, water, milk, oil or broth, and the converter needs no ingredient for them.

Cups to fluid ounces chart

Fluid ounces back to cups

Divide the fluid ounces by 8: 6 fl oz is ¾ cup, 12 fl oz 1½ cups and 20 fl oz 2½ cups. A cup and a half is 12 fl oz. For amounts under a cup the converter also gives tablespoons: 3 fl oz is 6 tbsp.

Liquid and dry ounces: fluid ounces vs ounces of weight

The difference between fluid ounces and ounces of weight is the difference between volume and weight. When a recipe gives a dry ingredient in ounces, sometimes called dry ounces, it almost always means weight, and a cup of a dry ingredient does not weigh 8 ounces. A cup of flour (all-purpose, spooned and leveled) weighs 4.23 ounces; a cup of granulated sugar 6.98 ounces. Even water is a little over 8 ounces by weight: 8.33 ounces a cup at 20 °C. The weight ounce is the avoirdupois ounce, 28.35 grams.

To go from ounces of weight to cups, use the grams to cups converter and switch the unit to ounces, or start from a cup with cups to grams.

Cup size: ounces in metric, imperial and label cups

The 8 fluid ounces are US measures. Other cups hold different amounts, so the cup size changes the ounces:

• Metric cup (250 mL, the cup NIST's household guide proposes for metric kitchens): 8.45 fl oz US fluid ounces.
• Imperial cup: the converter counts it as half an imperial pint, and the imperial pint is 20 imperial fluid ounces (Weights and Measures Act 1985), so the cup is 10 fl oz imperial fluid ounces. The imperial fluid ounce is slightly smaller than the US one.
• US label cup: nutrition labels treat a cup as 240 mL and a fluid ounce as 30 mL (21 CFR 101.9), so the label cup is 8 of those rounded label ounces. In true US fluid ounces that 240 mL is 8.12 fl oz.

Sources

• 21 CFR 101.9 (US nutrition labeling)
• America's Test Kitchen baking conversion chart
• America's Test Kitchen, Baking Basics: Measuring Ingredients
• King Arthur Baking ingredient weight chart
• King Arthur Baking, How to measure flour
• NIST Chemistry WebBook (Standard Reference Database 69), water
• NIST Handbook 44, Appendix C
• NIST Special Publication 430, Household Weights and Measures
• USDA FoodData Central, FNDDS survey foods
• USDA FoodData Central, SR Legacy
• Weights and Measures Act 1985 (UK), Schedule 1

• Cups to mL converterA US cup is 236.6 mL: type cups, pick the cup your recipe uses, get milliliters.
• How many tablespoons in a cupA US cup is 16 tbsp: type cups, get tablespoons and teaspoons.
• How many cups in a quartA US quart is 4 cups: type quarts, pints or gallons and get cups.
• Grams to ounces converterOne ounce is 28.35 grams, for any ingredient: type grams, get ounces and pounds.
• Cups to grams converter and conversion tableOne US cup weighs 198 grams of granulated sugar but 227 grams of butter: pick the ingredient and type the cups.
• Grams to cups converterPick the ingredient, type the grams and get US cups and spoons, with the fill method the weight assumes.