Converting between Units (AQA GCSE Maths): Revision Note

Converting units

How do I convert units of lengths?

• For metric units, conversion can be done by simply multiplying or dividing by powers of 10

• You need to know the basic conversions for length

  • 1 cm = 10 mm

  • 1 m = 100 cm

  • 1 km = 1000 m

• You need to decide whether to multiply or divide by the conversion factor

  • Ask, does the number of units increase or decrease?

    • The number of mm is 10 times bigger than the number of cm so mm = cm × 10

• You can do the conversion in stages

  • First convert kilometres into metres then metres into centimetres

How do I convert units of mass?

• For metric units, conversion can be done by simply multiplying or dividing by powers of 10

• You need to know the basic conversions for mass

  • 1 g = 1000 mg

  • 1 kg = 1000 g

  • 1 tonne = 1000 kg

How do I convert units of volume/capacity?

• For metric units, conversion can be done by simply multiplying or dividing by powers of 10

• You need to know the basic conversions for capacity

  • 1 litre = 100 cl = 1000 ml

    • 1 cl = 10 ml

• You must know the basic conversion between volume and capacity 

  • 1 ml = 1 cm³

  • 1 litre = 1000 ml = 1000 cm³

  • 1 m³ = 1000 litres