# Units of Length

**Standard Units**

You are probably familiar with a lot of these measurements. Length is about a distance. These **distances** answer questions with “how far?”, “how long?”, and “how high?”.

1 foot = 12 inches (inches are usually divided into sixteenths on a ruler)

1 yard = 3 feet = 36 inches

1 mile = 1,760 yards = 5,280 feet = 63,360 inches

**Metric Units**

The basis of length units for the metric system is the **meter**. A meter is about the same length of one yard. You already read that the metric system is based on units of ten so here’s a starter list, but they go on forever.

1 centimeter = 10 millimeters

1 meter = 100 centimeters = 1,000 millimeters

1 kilometer = 1,000 meters = 100,000 centimeters = 100,000,000 millimeters = 1*10^{8} millimeters

**Conversion**

You’re going to have to go back and forth with units. Converting inches into centimeters and feet into meters is a regular thing in math and science classes. Here are a few conversions. Technically you only need one conversion, but sometimes it’s easier to use one closer to the values you want.

1 inch = 2.54 centimeters = 25.4 millimeters

1 foot = 30.48 centimeters

1 yard = 0.91 meters

1 mile = 1.6 kilometers

1 millimeter = 0.04 inches

1 centimeter = .39 inches = 0.0325 feet

1 meter = 3.28 feet

1 kilometer = 0.62 miles

Example

So if I’m going to run a 5K race over the weekend, how many miles will I run?

5 kilometers = 5 * 0.62 miles = 3.1 miles