Metric units of length review (mm, cm, m, & km)

CCSS Math: 4.MD.A.1, 5.MD.A.1
Review the size of millimeters, centimeters, meters, and kilometers and how to convert between them.  Then, try some practice problems.

Summary of metric units of distance

KilometerMeterCentimeterMillimeter
1\goldD110001000100,000100{,}0001,000,0001{,}000{,}000
11000\dfrac{1}{1000}1\goldD110010010001000
1100,000\dfrac{1}{100{,}000}1100\dfrac{1}{100}1\goldD11010

What is distance?

Distance measures length. For example, the distance of a road is how long the road is.
In the metric system of measurement, the most common units of distance are millimeters, centimeters, meters, and kilometers.

How big are metric units of distance?

A paper clip is about 11 millimeter thick.
A fingernail is about 11 centimeter wide.
The length of a guitar is about 11 meter.
A kilometer is equal to 10001000 meters. It is a little over half of a mile.
Want to learn more about metric units of distance? Check out this video.

Practice set 1: Estimating distance

Problem 1A
Identify the most reasonable unit to measure the distance from New York to California.
Choose 1 answer:
Choose 1 answer:
Want to try more problems like this? Check out this exercise.

Converting larger units to smaller units

1 centimeter=10 millimeters1 \text{ centimeter} = \greenD{10}\text{ millimeters}
1 meter=100 centimeters1 \text{ meter} = \greenD{100}\text{ centimeters}
1 meter=1,000 millimeters1 \text{ meter} = \greenD{1,000}\text{ millimeters}
1 kilometer=1,000 meters1 \text{ kilometer} = \greenD{1,000}\text{ meters}
To convert larger units to smaller units we multiply the number of larger units by the green conversion factor for the appropriate smaller units.
Example: Converting meters to centimeters:
1 meter=100 centimeters1 \text{ meter} = \greenD{100}\text{ centimeters}
11 meters=11×100=1100 centimeters\blueD{11} \text{ meters} = \blueD{11}\times \greenD{100}=\blueD{11}\greenD{00}\text{ centimeters}

Converting smaller units to larger units

1 millimeter=110 centimeter1 \text{ millimeter} = \dfrac1{\purpleD{10}} \text{ centimeter}
1 centimeter=1100 meter1 \text{ centimeter} = \dfrac1{\purpleD{100}} \text{ meter}
1 meter=11,000 kilometer1 \text{ meter} = \dfrac1{\purpleD{1,000}} \text{ kilometer}
To convert smaller units to larger units we divide the number of smaller units by the purple conversion factor for the appropriate larger units.
Example: Converting meters to kilometers:
1 meter=11000 kilometer1\text{ meter}= \dfrac1{\purpleD{1000}} \text{ kilometer}
7 m=71000=7÷1000=0.007 km\maroonD{7} \text{ m}= \dfrac{\maroonD{7}}{\purpleD{1000}} = \maroonD{7}\div\purpleD{1000}=\blueD{0.007}\text{ km}
Want to learn more about converting between metric units of distance? Check out this video.

Practice set 2: Converting distance units

Practice 2A
Convert.
55 meters ==
millimeters
Want to try more problems like this? Check out these exercises:
Convert larger units to smaller units
Converting between units