Compost calculator

Knowing the area of your garden in square metres (m²) is essential when ordering compost or other garden materials.

How to measure your garden area

Whether your garden is a simple rectangle, an L-shape, or a complex combination of shapes, we've got easy tips to help you measure accurately.

Tips for accurate measuring

Use a tape measure: Always measure at least twice to double-check your numbers.
Break down irregular shapes: Divide complex shapes into simpler ones and calculate each separately.

Simple rectangle

The easiest shape to measure and generally applicable to raised beds and planters. You can use our calculator below to help determine the amount of compost you'll need, based on the depth you want to spread it.

Formula: Length × Width = Area

Example: If your garden bed is 4m long and 3m wide: 4m × 3m = 12m²

L-shaped areas

For gardens shaped like an "L", split the area into two rectangles, measure each separately, then add them together.

Example:

Rectangle A: 4m × 2m = 8m²
Rectangle B: 3m × 2m = 6m²

Total area: 8m² + 6m² = 14m²

Triangular areas

Triangles often appear in irregular gardens.

Formula: (Base × Height) ÷ 2 = Area

Example: A triangular flower bed with a 3m base and a 4m height: (3m × 4m) ÷ 2 = 6m²

Parallelogram areas

A parallelogram is a slanted rectangle.

Formula: Base × Height = Area

Example: Base of 5m and height of 3m: 5m × 3m = 15m²

Circular areas

Ideal for measuring circular flower beds or lawns.

Formula: π (3.14) × Radius² = Area

Example: A circle with a radius of 2m: 3.14 × (2m × 2m) = 12.56m²

Round up slightly

When ordering compost, it's better to have a little extra than not enough!