Definition
US customary units
US customary units are units used mainly in the United States, including inches, feet, pounds, cups, and gallons.
What it means
These units come in several different step sizes. Length can move from inches to feet to yards, mass or everyday weight from ounces to pounds, and liquid capacity from cups to pints to quarts to gallons. Unlike metric units, the steps are not all groups of ten, so use the relationship for the units in the question.
Remember it
Customary unit ladders have different step sizes: 12, 3, 16, 2, 2, and 4.
Example
A ribbon is 2 yards long. Because 1 yard = 3 feet, 2 × 3 = 6. The same ribbon is 6 feet long.
Watch for
A US liquid gallon and an Imperial gallon are different sizes, so use the measurement system named in the problem.
Common mix-up
An ounce measures mass, while a fluid ounce measures liquid volume; the word “fluid” changes the kind of measurement.
Exact meaning
US customary units are a system of measurement traditionally used in the United States. Common relationships include 12 inches = 1 foot, 3 feet = 1 yard, 16 ounces = 1 pound, 2 measuring cups = 1 liquid pint, 2 liquid pints = 1 liquid quart, and 4 liquid quarts = 1 gallon.