U.S. customary units

The US customary system of measurement is the measurement system used most commonly in the United States. Inside the US, it is sometimes referred to as simply the "customary" or "standard" system, or more formally "traditional systems of weights and measures." It was brought to the US by colonists from England, and is based on English units, the system used in England prior to its replacement by the imperial system. These systems share many units of measurement, though their values may differ in definition.

Although the US has not adopted The International System of Units (SI) as a country, SI units are still used in areas such as science, medicine, industry, the government, and the military. US customary units are mostly used in everyday life and commercial activities.

The US customary system includes units for measuring length, weight, capacity, area, volume, and temperature.

Length

Commonly used units for measuring length in the US customary system include inches (in), feet (ft), yards (yd), and miles (mi).

12 in = 1 ft

3 ft = 1 yd

5,280 ft or 1,760 yd = 1 mi

Weight

Commonly used units for measuring weight in the US customary system include ounce (oz), pound (lb), and ton (T).

16 oz = 1 lb

2,000 lb = 1 T

Capacity

Commonly used units for measuring capacity in the US customary system include teaspoons (t), tablespoons (T), cups (C), pints (pt), quarts (qt), and gallons (gal).

3 t = 1 T

16 T = 1 C

2 C = 1 pt

2 pt = 1 qt

4 qt = 1 gal

Fluid ounces (fl oz) are also used for measuring capacity.

1 fl oz = 2 T

8 fl oz = 1 C

16 fl oz = 1 pt

32 fl oz = 1 qt

Area

Square units are used for measuring area. In the US customary system, these include in2, ft2, and yd2.

144 in2 = 1 ft2

9 ft2 = 1 yd2

Acres and mi2 are also used for measuring area.

1 acre = 43,560 ft2

640 acres = 1 mi2

Volume

Cubic units are used for measuring volume. In the US customary system these include in3, ft3, and yd3.

1,728 in3 = 1 ft3

27 ft3 = 1 yd3

Temperature

The Fahrenheit (°F) scale is used for measuring temperature in the US customary system. Two reference points for this temperature scale are:

32 °F the freezing point of water
212 °F the boiling point of water