# 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
February 2024

# 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
February 2024

# 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
February 2024

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 football practice, or seeing how tall you’ve 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 250 millilitres of liquid, and if you have 1 tablespoon (tbsp) of flour, a unit conversion tells you that 1 tablespoon is the same as 3 teaspoons (tsp).

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

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## 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 kilometres if they sign up for the popular ‘5K’ race distance.

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

## How to convert units of measurement

When you’re 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’re 5 feet tall and you want to know your height in inches, multiply:

5 x 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.

## Explore unit conversions with DoodleMaths

Want to learn more about measurement? DoodleMaths is an award-winning app that’s filled with thousands of questions exploring multiplication, division and more!

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## Unit conversion tables

Length

1 centimetre = 10 millimetres
1 metre =1,000 millimetres
1 metre = 100 centimetres
1 kilometre = 1,000 metres
1 inch = 2.54 centimetres
1 foot = 30.48 centimetres
1 yard = 0.91 metres

Weight

1 kilogram = 1,000 grams
1 gram = 1,000 milligrams
1 tablespoon = 14.17 grams
1/2 tablespoon = 8.53 grams
1 teaspoon = 5.69 grams
1/2 teaspoon = 2.84 grams

Volume

1 liter = 1,000 millilitres
1 pint = 568.26 millilitres
1 gallon = 8 pints

## Practice problems for unit conversions

The following problems are a great way to practise measurement conversions. After you’re done, head over to our maths app for more unit conversion and maths 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 centimetres into millimetres. Show your work.

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

Piper has 7 meters 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-metre distance in one run. How many kilometres does she cover? Show your work.

D

4×12= 48 inches

150 millimetres.

15×10=150 millimetres

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 have enough ribbon to make a wreath! There are 0.91 meters in a yard, so:

7×0.91= 6.37 feet

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

Lesson credits

Katie Wickliff

Katie holds a master’s degree in Education and a bachelor’s degree in both Journalism and English. She has over 15 years of experience as a teacher and is also a certified tutor. Most importantly, Katie is the mother of an 8 and 11-year-old. She's passionate about education and firmly believes that the right tools and support can help every child reach their full potential.

Katie Wickliff

Katie holds a master’s degree in Education and a bachelor’s degree in both Journalism and English. She has over 15 years of experience as a teacher and is also a certified tutor. Most importantly, Katie is the mother of an 8 and 11-year-old. She's passionate about education and firmly believes that the right tools and support can help every child reach their full potential.

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