Metric Units

Metric Units

Basic, GCSE(F),

The three common metric units are metre for length, litre for capacity and gram for mass.

Metric units are based on powers of 10, and the metric units (metre, gram, litre) are prefixed to indicate which power of 10 is being used:

milli means a thousandth (`frac(1)(1000)`)

centi means a hundredth (`frac(1)(100)`)

kilo means a thousand

1 kilometre (km) = 1000 metres (m)
1 metre (m) = 100 centimetres (cm)
1 centimetre (cm) = 10 millimetres (mm)

1 tonne (t) = 1000 kilograms (kg)
1 kilogram (kg) = 1000 grams (g)

1 litre (l) = 1000 millilitres(ml)

1 cm3 = 1 millilitre (ml)

To convert between amounts, set up a small table for the conversion. On the first line, show the conversion rate. On the second line, put in the value to convert.


1. Dylan is putting up a shelf in an alcove. The alcove measures 1058mm. The shelf is 103cm long. Dylan reckons that the shelf can be up to 4cm smaller than the alcove. Will the shelf fit?

Answer: Yes

Change the alcove from mm to cm:

1058 ÷ 10 = 105.81058

Work out the smallest size the shelf can be: 105.8 - 4 = 101.8cm. The shelf is larger than the minimum and smaller than the alcove, so it will fit.

2. Mia is measuring out some liquid for a chemistry experiment. She needs 520cm3. What is this in litres?

Answer: 0.520 litres

Change cubic centimetres to millilitres: 520cm3 = 520ml.

520 ÷ 1000 = 0.520520

Going from millilitres to litres is a division: litres.