Numbers

3. Decimals

3.2. Metric measures

The metric system is a decimal based measuring system, in use internationally.

Basic metric units of measurement are summarised below.


Metre

The metre is the basic metric unit for measuring length, for example distance and height.

Smaller measurements, for example when using a ruler or tape measure, include centimetres and millimetres. The ruler below measures up to 15 centimetres, each of which is divided into 10 millimetres.

A ruler showing 15 centimetres, each divided into 10 millimetres

mbnachhilfe_de atPixabay / Licence

  • 1 centimetre = 0.01 metres, one hundredth of a metre.
  • 1 millimetre = 0.1 centimetres, one tenth of a centimetre.

Larger measurements, for example distances between places, are taken in multiples of metres, most commonly the kilometre.

  • 1 kilometre = 1000 metres.

Litre

The litre is the basic metric unit for measuring volume, for example of liquids.

In everday life, liquids are sold, or measured, in multiples of litres (e.g. 2.5 litres) or in millilitres.

  • 1 litre = 1000 millilitres.
  • 500 millilitres = 0.5 litres, or half a litre.
A jug with 500 ml and 250 ml measures on side

Gram

The gram is the basic metric unit for measuring weight, for example when you are weighing ingredients for a recipe.

In everyday life, larger quantities, such as your own weight, are measured in kilogrammes.

  • 1 kilogram = 1000 grams.