Customary units of length are units used in the United States to measure how long or how far something is. The four main units are inches, feet, yards, and miles.
Customary units are often used for everyday measurements in the United States, such as height, distance, and length.
To convert customary units of length, you multiply or divide by a conversion factor that tells how many smaller units are in a larger unit, or vice versa.
Remember: The smaller the unit, the more of them you need to make up the larger unit.
These are the most common conversions you should memorize to help you compare and solve problems involving customary length.
Use these conversions to solve word problems, estimate distances, or check your work when comparing lengths.
When you compare two measurements, make sure they are in the same unit. You can convert one or both measurements before comparing.
Always compare using the same unit. Choose the unit that makes the math easier to work with.
Customary length units are used every day — in sports, construction, travel, and even clothing sizes. Knowing how to convert and compare them helps you make sense of real-world measurements.
Understanding length conversions helps you reason about size, distance, and scale — skills you use every day in math and beyond.