Units and Conversions

Being able to convert between different units of measurement is a fundamental skill tested throughout the AQA GCSE Mathematics course. You need to convert between metric units, understand common imperial units, and convert between compound units. This lesson provides all the key conversions and methods you need.

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Metric Units of Length

Unit	Abbreviation	Relationship
Kilometre	km	1 km = 1,000 m
Metre	m	1 m = 100 cm
Centimetre	cm	1 cm = 10 mm
Millimetre	mm	Base unit for small measurements

Converting Metric Lengths

graph LR
    A[km] -->|x 1000| B[m]
    B -->|x 100| C[cm]
    C -->|x 10| D[mm]
    D -->|/ 10| C
    C -->|/ 100| B
    B -->|/ 1000| A

• To convert from a larger unit to a smaller unit, multiply.
• To convert from a smaller unit to a larger unit, divide.

Worked Example 1: Convert 3.7 km to metres.

• 3.7 x 1,000 = 3,700 m

Worked Example 2: Convert 450 cm to metres.

• 450 / 100 = 4.5 m