Units of measure - AQAChanging between units of measurement

There are two systems used for measuring quantities - metric and imperial.

The metric system uses three main units for measuring:

• length in metres (m)
• mass in kilograms (kg)
• volume in cubic metres (m³)

The imperial system uses the following units:

• length in inches, feet and yards
• mass in pounds (lb), ounces (oz) and stones
• volume in gallons

Converting metric units of length

The most common metric unit conversions for length are:

• 1 km = 1,000 m
• 1 m = 100 cm
• 1 cm = 10 mm
• 1 m = 1,000 mm

These can be used to convert the units used to measure length.

Example

The sunflower is 214 cm tall. Calculate the height of the sunflower in:

(a) metres

(b) millimetres

(a) 1 metre = 100 centimetres

(b) 1 centimetre = 10 millimetres

1 metre is longer than 1 centimetre, so to convert from metres to centimetres, multiply by 100. 1 millimetre is shorter than 1 centimetre so to convert from millimetres to centimetres, divide by 10.