How much landscape supply do I need?

The formula

Measure the area in metres and decide how deep the material needs to be. Then multiply:

Length (m) × Width (m) × Depth (m) = cubic metres (m³)

Depth is usually given in millimetres, so divide by 1,000 first: 75mm is 0.075m, 100mm is 0.1m.

Typical depths

These are common starting points. Your landscaper or engineer’s spec always takes priority.

A worked example

A garden bed 10m long and 4m wide, mulched 75mm deep: 10 × 4 × 0.075 = 3 m³. That is the amount to order.

Round up, not down

Ground is rarely perfectly flat and loose material settles once it is spread. Round up to the nearest half cubic metre (our volume calculator adds 5% automatically) so you are not caught short halfway through the job.

Turf is different

Turf is sold by the square metre, so for turf you only need length × width. Add about 5% for cuts around edges and curves.

Worked examples

These use the same maths as our volume calculator: length × width × depth, with depth converted from millimetres to metres.

• Garden bed: 6m × 1.5m at 200mm deep = 6 × 1.5 × 0.2 = 1.8 m³. Order 2 m³.
• New lawn soil: 10m × 5m at 100mm deep = 5 m³ of under turf soil.
• Turf for the same lawn: 50 m², plus about 5% for cuts and edges = 53 m².
• Mulch: 20 m² of garden at 75mm deep = 1.5 m³.

Odd shapes and curved beds

Most yards are not neat rectangles. Break the area into simple shapes, work out each one and add them together. A triangle is half of length × width. A circle is 3.14 × radius × radius. For a curved bed, measure the length along the middle of the curve and use the average width.

Allowing for compaction

Materials that get compacted, like road base and crusher dust, end up thinner than they are spread. As a rule of thumb, order around 15–20% more than the finished volume so you still reach the depth you need after compaction. Soil also settles a little after watering, so round garden soil up rather than down.

Cubic metres and tonnes

We sell most products by the cubic metre, but every product has a different weight per cubic metre. Sand and road base are much heavier than mulch. That matters for wheelbarrow trips and for how much a truck can carry in one load. Each product page lists its approximate weight, and we work out the right truck when we quote.