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cup — Definition, Formula & Examples

A cup is a unit of volume used in the US customary system that equals 8 fluid ounces. It is commonly used in cooking and everyday measurement.

One US customary cup (c) is defined as exactly 8 US fluid ounces, which equals 12\frac{1}{2} of a US pint, or approximately 236.588 milliliters.

Key Formula

1 cup=8 fl oz=12 pint=14 quart=116 gallon1\text{ cup} = 8\text{ fl oz} = \tfrac{1}{2}\text{ pint} = \tfrac{1}{4}\text{ quart} = \tfrac{1}{16}\text{ gallon}
Where:
  • fl oz\text{fl oz} = US fluid ounces
  • cup\text{cup} = US customary cup

How It Works

Cups fit into a simple chain of US customary volume units. Two cups make 1 pint, 2 pints make 1 quart, and 4 quarts make 1 gallon. To convert cups to a larger unit, you divide; to convert to a smaller unit, you multiply. For example, to find how many cups are in a gallon, multiply: 4×2×2=164 \times 2 \times 2 = 16 cups per gallon.

Worked Example

Problem: A recipe calls for 6 cups of water. How many quarts is that?
Recall the conversion: There are 4 cups in 1 quart.
1 quart=4 cups1\text{ quart} = 4\text{ cups}
Divide: Divide the number of cups by 4.
6÷4=1.56 \div 4 = 1.5
Answer: 6 cups equals 1.5 quarts (1 and a half quarts).

Visualization

Why It Matters

Cups appear constantly in recipes and food packaging. Understanding cup conversions helps you scale recipes up or down and is a key skill in elementary measurement standards.

Common Mistakes

Mistake: Confusing cups with fluid ounces and thinking 1 cup = 16 fl oz.
Correction: One cup equals exactly 8 fluid ounces, not 16. A pint is the unit that equals 16 fluid ounces.

Related Terms