How much gravel, sand or topsoil do I need?

Start with area and planned depth

Measure the length and width in metres. For a rectangular area, multiply length by width to get square metres. Divide the planned depth in millimetres by 1,000 to convert it to metres.

Volume in cubic metres = area in square metres × depth in metres.

A worked example

An area 5 metres long and 4 metres wide is 20m². At a planned depth of 50mm, its volume is 20 × 0.05 = 1m³. The depth here is an arithmetic example, not a recommended installation depth.

Volume alone does not tell you the weight. If the confirmed density for your material were 1.6 tonnes per cubic metre, this example would require 1.6 tonnes before any allowance. At a listed 800kg per bag, that would equal two bags. Density varies by material and condition: use the density confirmed for your order.

Allow for the actual job

Uneven ground and separate sections can change the volume. Calculate each section separately and add the results. For compacted layers, ask your installer for the required finished depth and material allowance before ordering. Avoid applying one allowance to every material.

Weight and volume are different

For aggregate products sold by weight, use the confirmed density to convert volume to tonnes. For products sold by volume, one cubic metre equals 1,000 litres. Read the product page for the listed bag size, then round up to whole bags if that is the format you choose.

Open the quantity calculator

Send us the material, area, planned depth and postcode so we can check your estimate and quote the available supply format.