# Imperial units

## In a nutshell

The imperial unit system is another set of units that are not used as much nowadays, but are still seen in specific circumstances.

### Imperial units

Here is a table of imperial units:

#### Measurement | #### Units |

Length | Inches, feet, yards, miles |

Area | Square inches, square feet, square miles |

Volume | Cubic inches, cubic feet, gallons, pints |

Mass | Ounces, pounds, stones, tons |

Speed | Miles per hour (mph) |

**Note: **Tons and tonnes are two different units of measure!

## Converting between units

While there is no need to memorise any conversions related to imperial measurements, it is still important to be familiar with them when converting from either one imperial unit to another, or an imperial unit to a metric unit.

##### Example 1

*A bird weighs $3$ pounds. Given that $1$ pound $=16$ ounces, how much does the bird weigh in ounces?*

*The conversion rate is given:*

$1$ *pound* $=16$ *ounces*

*Multiply both sides by $3$ to find what $3$ pounds is equivalent to:*

$3$ *pounds $=16\times3$ ounces*

$3$* pounds $=48$ ounces*

*The bird weighs *$\underline{48 \ \text{ounces}}$.

##### Example 2

*Give an approximate conversion of $30$ pints to gallons to $1$ decimal place, given that $1$ litre $\approx1.75$ pints, and $1$ gallon $\approx4.5$ litres.*

*First, convert the $30$ pints to litres:*

$1$ *litre $\approx 1.75$ pints*

$1$ *pint $\approx \frac{1}{1.75}$ litres*

$30$ *pints $\approx (\frac{1}{1.75}\times30)$* *litres*

$30$ *pints $\approx17.14$ litres*

*Then, convert the $17.14$ litres to gallons:*

$1$ *gallon $\approx4.5$ litres*

$1$ *litre $\approx \frac{1}{4.5}$ gallons*

$17.14$ *litres $\approx (\frac{1}{4.5}\times17.14)$ gallons*

$17.14$ *litres $\approx3.8095....$ gallons*

$\underline{30 \ \text{pints} \approx3.8 \ \text{gallons} \ (1.d.p)}$