The area of a square or rectangular garden is easy to calculate. Simply multiply the length by the width by the depth: For example: 5 metres long by 2 metres wide by 10cm (0.1 metres) deep is 5 x 2 x0.1 = 1m³

For odd-shaped gardens try to average the width & length.

Circular areas use the formulae: Area = 3.1415 x radius x radius (where the radius is half the distance across the circle).

The quantity of concrete mix is worked out in the same way.