Capacity in Math – Definition with Examples

Home » Math Vocabluary » Capacity in Math – Definition with Examples

What is Capacity in Math?

Have you observed that when you fill water in a pan or a bottle, there is only a certain amount of water you can fill in them? All the sodas and chocolate syrups have a maximum amount mentioned on their containers. This certain amount that the pan, bottle, or any other container can hold is called capacity. In mathematics, capacity is defined as the maximum quantity a container can hold when full.

Units of capacity

There are two types of capacity measurement: metric measurement and customary measurement.

Metric Measurement 

The standard units to measure capacity are liters and milliliters.

Milliliter (ml): Milliliter is denoted by the letters ml. A milliliter is a unit to measure very small quantities of liquids like cough syrup.

Liter (l):  Liter is denoted by the letter l. A liter measures liquids like juice, milk, water, and so on.

The units’ milliliter (ml) and liter (l) are related: 

One liter is equal to a thousand milliliters.

1l = 1000 ml  or 1000 ml = 1l  

Customary Measurement 

Customary measurement refers to gallons, quarts, pints, cups, and fluid ounces. This is US Standard Unit (English Unit or Customary Unit).

Customary units of volume and capacity

Fluid Ounce: A fluid ounce is a unit used to measure the volume of liquids. It is commonly abbreviated as fl. oz.

Cup: A cup is a unit of volume measurement equal to 16 tablespoons. A US cup is about 237 ml. It is usually used for drinking beverages like coffee or tea.

Pint: A pint is equal to 2 cups. A US pint is about 473 ml. We express the capacity of juice jars in pints.

Quart: A quart (qt) is the same as 2 pints. The capacity of milk cartons is expressed in quarts.

Gallon: A gallon (gal) is the largest liquid measurement. It is the same as 4 quarts. The capacity of fuel tanks is expressed in gallons.

Conversion chart for customary units of capacity

Solved Examples

Example 1. Susie bought 4 liters of orange juice. She wants to convert this quantity into milliliters. Can you help her?


We know that 1l = 1000 ml

So, 4l = 4 ✕ 1000 ml = 4000 ml

Therefore, the quantity of orange juice bought by Susie in milliliters is 4000 ml.

Example 2. Ray bought 6 gallons of paint to decorate his house. Help him convert the quantity of paint to quarts.


We know that 1 gallon = 4 quarts

So, 6 gallons = 6 ✕ 4 quarts = 24 quarts

Therefore, the quantity of paint bought by Ray is 24 quarts.

Example 3. Danny drank 2 cups of an energy drink on Monday. How much quantity is that in fluid ounces?


We know that 1 cup = 8 fluid ounces

So, 2 cups = 2 ✕ 8 fluid ounces = 16 fluid ounces

Therefore, the quantity of energy drink Danny drank was 16 fluid ounces.

Practice Problems

Capacity in Math – Definition with Examples

Attend this Quiz & Test your knowledge.


Jack made 4 pints of lemonade. If he divided it into an equal number of paper cups, how many paper cups would he need?

16 cups
32 cups
20 cups
8 cups
Correct answer is: 8 cups
A pint is equal to 2 cups.
So, 4 pints = 4 ✕ 2 cups = 8 cups.

Convert 4.5 liters into milliliters.

450 ml
4500 ml
45 ml
45000 ml
Correct answer is: 4500 ml
We know that 1 l = 1000 ml
So, 4.5 l = 4.5 ✕ 1000 ml = 4500 ml

Convert 12 cups to pints.

24 pints
8 pints
6 pints
4 pints
Correct answer is: 6 pints
We know that 1 pint is equal to 2 cups.
So, 1 cup is half of a pint.
So, 6 cups in pints = 12 ÷ 2 = 6 pints.

Aisha’s mom poured 3 quarts of chocolate milk into an equal number of cups for children at a sleepover. How many cups did she use?

6 cups
12 cups
9 cups
15 cups
Correct answer is: 12 cups
A quart is equal to 4 cups. So, 3 quarts = 3 ✕ 4 cups = 12 cups.

Frequently Asked Questions

Capacity measures the maximum amount of a liquid that a container can hold when full.

The U.S. customary capacity or volume measurement units are ounces, cups, pints, quarts, and gallons.

A liter is the standard unit of capacity, and the smaller unit of capacity is a milliliter. In short, a liter is written as ‘l’ and milliliter as ‘ml.’ Liter (l) and milliliter (ml) are related to each other as 1 liter = 1000 milliliter (1 l = 1000 ml).