# How to Do Unit Conversions

Converting units of measurement is an essential part of working with world measurement systems. Let’s learn the basics of unit conversions!

Author
Katie Wickliff

Published
November 8, 2023

# How to Do Unit Conversions

Converting units of measurement is an essential part of working with world measurement systems. Let’s learn the basics of unit conversions!

Author
Katie Wickliff

Published
Nov 8, 2023

# How to Do Unit Conversions

Converting units of measurement is an essential part of working with world measurement systems. Let’s learn the basics of unit conversions!

Author
Katie Wickliff

Published
Nov 8, 2023

Key takeaways

• The two main measurement systems are metric and customary. Most of the world uses the metric system, but the United States uses the customary system.
• To convert from a larger unit to a smaller unit, multiply.
• To convert from a smaller unit to a larger unit, divide.

Whether you’re checking the weather, determining how long it will take to get to soccer practice, or seeing how tall your child has grown in the past year, measurement is everywhere.

Often, you’ll need to convert units of measurement from one form to another. For instance, a recipe might call for 16 fluid ounces of liquid, and if you only have measuring cups, a unit conversion tells you that 16 ounces is the same as two cups.

In this article, we’ll cover the basic measurement conversion rules and explain how to convert units of length measurement, weight measurement, and volume measurement in both customary and metric systems

## What are Unit Conversions?

First, let’s define the term “unit” as it relates to measurement. A unit of measurement is a system that describes the size of something. Unit conversions take the measurement of something in one set of units and change it to an equal measurement in another set of units.

## Why are Unit Conversions Important?

Converting between measurement units is important when working within and between measurement systems. There are two systems of measurement used worldwide: the metric system and the imperial (or customary) system. Most of the world uses the metric system, but a few countries, including the United States, use the customary system.

The conversion of units is important because it enables us to use different systems and scales to share measurements, which allows for collaboration with other countries.

Unit conversion is also important to calculate and compare measurements between systems. For example, a runner who normally measures their training runs by miles will need to understand the unit conversion of miles to kilometers if they sign up for the popular “5K” race distance.

Even within the United States, industries have varying needs and preferences when it comes to measurement systems. For example, the customary system is often used for consumer products and industrial manufacturing, while the metric system is most often used in fields like science and medicine.

## How to Convert Units of Measurement

When your student is first learning unit conversions, it helps to have a few basic guidelines.

Rule 1: When converting from a larger unit to a smaller unit, multiply.

Example: If you are 5 feet tall and you want to know your height in inches, multiply:
5×12=60 inches

Rule 2: When converting from a smaller unit to a larger unit, divide.

Example: If your older brother is 72 inches tall, and you want to know how many feet tall he is, divide:
72/12= 6 feet

This basic rule applies to all conversions, no matter the object being measured or the system you’re using.

## Unit Conversion Tables

Length

Metric System
1 kilometer = 1,000 meters
1 meter = 100 centimeters
1 meter =1,000 millimeters
1 centimeter = 10 millimeters

Customary System
1 mile = 5,280 feet
1 mile = 1,760 yards
1 yard = 3 feet
1 foot = 12 inches

Weight

Metric System
1 kilogram = 1,000 grams
1 gram = 1,000 milligrams

Customary System
1 ton = 2,000 pounds
1 pound = 16 ounces

Volume

Metric System
1 liter = 1,000 milliliters

Customary System
1 gallon = 4 quarts
1 quart = 2 pints
1 pint = 2 cups
1 cup = 8 fluid ounces

## Practice Problems for Unit Conversions

The following problems use the metric and customary systems and are a great way to practice measurement conversions. After you’re done, head over to Doodle Learning’s math app for more unit conversion and math conversion practice.

Your little sister is 4 feet tall. What is her height in inches? Show your work.

1. 60 inches
2. 30 inches
3. 43 inches
4. 48 inches

Convert 15 centimeters into millimeters. Show your work.

An athlete tries to drink a gallon of water each day, but his water bottle measures 1 quart. How many full water bottles does the athlete need to drink to achieve his daily goal?

Piper has 3 yards of ribbon on a roll. She needs 15 feet of ribbon to make a wreath. Does she have enough? Explain your thinking.

A runner covers a 10,000-meter distance in one run. How many kilometers does she cover? Show your work.

D

4×12= 48 inches

150 millimeters.

15×10=150 millimeters

He would need to drink 4 full water bottles to achieve his goal. There are 4 quarts in 1 gallon, so:

4×1=4 quarts

Piper does not have enough ribbon to make a wreath. There are 3 feet in 1 yard, so:

3×3= 9 feet

The runner covers 10 kilometers during her run. 10,000/1,000= 10 kilometers

## FAQs about the conversion of units

KHDDCM stands for “King Henry Died Drinking Chocolate Milk,” which is an acronym to help students remember measurement increments in the metric system.

King Henry Died Drinking Chocolate Milk is a mnemonic device that helps students remember metric measurement increments: Kilo, Hecto, Deca, Unit, Deci, Centi, Milli.

Lesson credits

Katie Wickliff

Katie holds a master’s degree in Education from the University of Colorado and a bachelor’s degree in both Journalism and English from The University of Iowa. She has over 15 years of education experience as a K-12 classroom teacher and Orton-Gillingham certified tutor. Most importantly, Katie is the mother of two elementary students, ages 8 and 11. She is passionate about math education and firmly believes that the right tools and support will help every student reach their full potential.

Katie Wickliff

Katie holds a master’s degree in Education from the University of Colorado and a bachelor’s degree in both Journalism and English from The University of Iowa. She has over 15 years of education experience as a K-12 classroom teacher and Orton-Gillingham certified tutor. Most importantly, Katie is the mother of two elementary students, ages 8 and 11. She is passionate about math education and firmly believes that the right tools and support will help every student reach their full potential.

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