Measuring Capacity

We use spoons, jugs, glasses, beakers, bowls, barrels, bottles, pitchers, cartons, cans, and the like to store liquids.

 We take medicine in a fluid ounce.

The capacity of a tablespoon is nearly half a fluid oz.

The capacity of 25 teaspoons is nearly equal to half a cup.

The capacity of a car's fuel tank is about 15 gallons. A fish tank can hold 6 gallons.

A \(10 x 10 x 10\) inch carton cube can hold 4 gallons of paint. 

How do we measure them? 

Capacity is the amount of liquid that a container can hold.

In this mini-lesson, let us learn about measuring capacity, measure of capacity, the unit of capacity, measure capacity worksheet, and measurement capacity.

Lesson Plan

The term capacity is used for measuring the volume of a liquid.

The amount of liquid that any container can hold is called its capacity.

Capacity Measurement

The American metric system is also called the United States Customary Units (USCS).

USCS follows 5 customary units to measure the capacity.

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How to Measure Capacity? 

To get the idea to measure capacity, we need to know the objects that hold liquids around us.

Units of capacity	Example
Fluid ounce	syrup or tonic
Cup	coffee or tea
Pint	juice jar
Quart	milk carton or water jar
Gallon	petrol or gasoline

Estimation

Let's find what most likely could be used for the capacity measurement by mere estimation.

Capacity	Units	Estimation
A perfume spray can hold	gallons / pints	pints
An eyedropper is closer to	a cup / a quart	cup
A mop bucket has	gallons / pints	gallons
A tea kettle holds in	cups / gallons	cups
A water pool measured in	quarts / gallons	gallons
A mayonnaise jar	quarts / pints	pints

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There are 5 customary units to measure capacity.

A fluid ounce is the smallest unit of measuring capacity and the gallon is the largest unit.

1 cup = 8 fl. oz

Gallon Chart

Use this gallon chart to make the conversions of customary units.

This gallon chart shows us that 1 gallon = 4 quarts  = 8 pints = 16 cups.

Capacity Conversion

You can multiply or divide according to the known unit and the required unit.

For Example:

1. \(4 \text{ quarts} = \text{____ pints }\)

From the chart we know that

\[\begin{align}1 \text{ quart} &= 2 \text{ pints}\\4 \text{ quarts} &= 4\times 2 \text{ pints}\\ &= 8 \text{ pints}\end{align}\]

2. \(6 \text{ pints} = \text{_____ quarts}\)

From the chart, we know that

\[\begin{align}1 \text{ pint} &= \dfrac{1}{2} \text{ quart}\\\\6 \text{ pints} &= 6\div 2 \\\\&= 3 \text{ quarts}\end{align}\]

8 fl oz	1 cup
16 fl oz	1 pint
32 fl oz	1 quart
128 fl oz	1 gallon

Measuring Capacity Example 

Sophie made 8 quarts of orange juice. She divided it into an equal number of cups. How many cups would she have used?

From the gallon chart, we understand that 4 quarts = 16 cups

Thus 8 quarts of juice will be divided into 32 cups.

\(\therefore\) she has used 32 cups to pour the orange juice.

Comparing Capacity Example

 A tall glass can hold 4 pints and a big mug can hold 50 fluid oz. Which one holds more?

We know that 4 pints  = 8 cups

and 8 fl. oz = 1 cup.

\[\begin{align} 50 \text { fl. oz} &= \dfrac{1}{8}\times 50\\&= 6 \dfrac{1}{4} \text{ cups}\end{align}\]

Thus on comparison we find that

\[8 \text{ cups} >  6 \dfrac{1}{4} \text{ cups}\]

\(\therefore\) the tall glass holds more.

Measurement Capacity 

Try solving the simulation below. Adjust the slider to measure the desired amount of gallon.

Click on the measuring beakers and verify how many beakers would you use to fill the gallon jar.

Example 3

 

 

John consumes 20 cups of water in the first 2 days of a week. Going at the same rate, how many quarts would he have consumed at the end of the week?

Solution

1 quart = 4 cups

If 4 cups = 1 quart then

20 cups \(= 20 \div 4 = 5\) quarts

In 2 days, he consumed 5 quarts.

Then in 7 days he consumed: \[\begin{align}\\&= \dfrac{5}{2} \times 7\\ &= \dfrac{35}{2} \\&= 17\dfrac{1}{2}\text{ quarts}\end{align}\]

\(\therefore\) John would have consumed \(17\dfrac{1}{2}\) quarts of water.

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