# What is capacity?

A thorough explanation of how to measure capacity with helpful conversion charts and practice questions

Author
Tess Loucka

Published
February 2024

# What is capacity?

A thorough explanation of how to measure capacity with helpful conversion charts and practice questions

Author
Tess Loucka

Published
February 2024

# What is capacity?

A thorough explanation of how to measure capacity with helpful conversion charts and practice questions

Author
Tess Loucka

Published
February 2024

Key takeaways

• The most used system of capacity measurement in the world is the metric system. Only 3 countries use the customary system: the United States, Liberia, and Myanmar.
• The metric system is centered around the litre. To measure larger or smaller amounts of something, multiples or fractions of the litre are used.

When a recipe calls for an ounce of milk or 1 teaspoon of baking soda, these measurements all refer to a very particular amount of something.

Every container, whether it be a teacup, a bathtub, or a barrel, can only hold a particular amount of liquid before it fills up, and this idea is referred to in science as capacity.

A glass can only be filled up so high with orange juice before it spills over. Similarly, a cereal bowl can only hold so much milk until it reaches the brim and drips down the sides.

When you take a bath and fill the tub with water, go to water your plants and fill up your watering can, or fill up a water gun when you’re at the beach, you’re really thinking about capacity!

Capacity is a measurement that can be used to better understand countless areas of your daily life and the world around you, but what is capacity and how do we measure it?

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## What is capacity in maths?

Here’s a simple definition of capacity: capacity refers to the amount of something that an object can hold before spilling over. Another capacity definition is the maximum amount of something—whether that be a solid, liquid, or gas—that fits into a given container.

There are two systems of measurement commonly used for measuring capacity—the metric system and the customary system. The metric system is far more common.

## Metric units of capacity

The metric system uses the units of litres (l), millilitres (ml), and other related units. One litre is equivalent to 1,000 millilitres. We can write that out as:

1 l = 1000 ml

Knowing that fact then allows us to gather a few more measurements:

½ l = 500 ml

¼ l = 250 ml

⅕ l = 200 ml

and so on…

Besides litres and millilitres, there are a few other units of measurement used in the metric system. They are as follows:

• Kilolitre =/1,000
• Hectolitre =/100
• Decalitre =/10
• Litre
• Decilitre =x10
• Centilitre =x100
• Millilitre =x1000

A unit of capacity listed lower a litre is larger. A unit of capacity above is smaller. To convert 1 litre to hectolitres, simply divide 1 by 100 to get 0.01 hectolitres. To convert 1 litre to millilitres, just multiply 1 by 1,000 to get 1,000 millilitres.

One way to remember the units of the metric system is to remember that “King Henry Died Unusually Drinking Chocolate Milk.” In this case, the U stands for unit of capacity, or litre!

## Explore capacity with DoodleMaths

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

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## Measuring capacity

Measuring capacity often requires you to have a tool called a graduated cylinder. These are cylindrical containers with marks on the side that measure its capacity.

If you have a container with an unknown capacity, you can fill the container with water, then pour that water into a graduated cylinder. The line on the cylinder at which the surface of the liquid is touching is the container’s capacity.

Measuring capacity can also be done by simple math and unit conversion. Let’s say you have a container with an unknown capacity. You can take a known amount of water, such as a cup, and fill the container up until it is full, taking note of exactly how many cups of water you poured in.

Estimating a container’s capacity can also come in handy and can be done easily with a firm understanding of the units of capacity measurement.

To put things into perspective:

• A swimming pool may have about 1,800 kilolitres of water.
• A bathtub, on average, holds about 302 litres.
• A typical bottle of water may hold 0.5 litres of water or 16.9 ounces.
• A tube of toothpaste might hold 75 ml or 2.5 ounces of toothpaste.

So, if you take a look at a bowl of cereal and want to estimate its capacity, what unit will you use? Kilolitres, litres, or millilitres? Your answer should be litres.

Understanding how units of capacity measurement work gives you a deeper understanding of the world around you. For more practice with capacity, look for a maths app or website with resources such as conversion charts and practice problems that will support you as you learn.

## Practice problems for measuring capacity

Click on the boxes below to see the answers!

Capacity is the amount of liquid that fits inside a container

Metric units of capacity are all related to the litre. The units are kilolitres, hectolitres, decalitres, litres, decilitres, centilitres, and millilitres.

The standard unit of capacity in science is the litre.

Lesson credits

Tess Loucka

Tess Loucka discovered her passion for writing in school and hasn't stopped writing since! Combined with her love of numbers, she became a maths and English tutor. Since graduating, her goal has been to use her writing to spread knowledge and the joy of learning to readers of all ages.

Tess Loucka

Tess Loucka discovered her passion for writing in school and hasn't stopped writing since! Combined with her love of numbers, she became a maths and English tutor. Since graduating, her goal has been to use her writing to spread knowledge and the joy of learning to readers of all ages.

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