# Imperial Units - Capacity

Lesson

In Introducing the Royal Measurements, we looked at some common imperial units for measuring capacity. Capacity is a measure of the amount something can contain, for example, how much juice will fit in a bottle. Here are a list of imperial capacity measurement units in order from smallest to largest: pints (pt), quarts (qt) and gallons (gal).

## Converting units

Converting units is an application of ratios. We start by writing the conversion equation and look at how we multiply or divide to find the value of a certain quantity. Make sure your familiar with applications of ratios, then you can look through the following conversion charts, so we can start moving between imperial and metric units.

### Metric units to imperial units

$1$1 litre = $2.11338$2.11338 pints

$1$1 litre = $1.05669$1.05669 quarts

$1$1 litre = $0.264172$0.264172 gallons

### Imperial units to metric units

$1$1 gallon = $3.78541178$3.78541178 litres

$1$1 quart = $0.946353$0.946353 litres

$1$1 pint = $0.473176$0.473176 litres

Hint

You may have noticed that there are a lot of decimals when converting metric to imperial, or vice versa. To make these conversions easier, just round them to $1$1 decimal place e.g. $1$1 pint$\approx$$0.5$0.5 litres.

#### Worked Examples

##### Question 1

Using the conversion $1$1 gallon $=$= $4.5$4.5 litres, change each of these capacities from gallons to litres:

1. $5$5 gallons

2. $10$10 gallons

3. $40$40 gallons

4. $16$16 gallons

##### Question 2

Using the approximate conversion $1$1 gallon $=$= $4.5$4.5 litres, change each of these capacities from litres to gallons.

Give your answers correct to $2$2 decimal places where necessary.

1. $10$10 litres

2. $50$50 litres

3. $100$100 litres

4. $25$25 litres

##### Question 3

A van has a petrol tank that holds $11$11 gallons of petrol. How many litres of petrol is that?

Use the approximation $1$1 gallon $=$= $4.5$4.5 litres.