Garden Soil Calculator
Find how much topsoil, compost or raised-bed mix you need to fill a bed, top-dress a border or level a lawn. Enter the size and depth and get the volume, weight, number of bags and bulk bags, with an allowance for settling.
Calculate garden soil
Garden soil formula
Volume
V = L × W × depth × beds × (1 + settling%)Weight and bags
Weight ≈ V × 1.3 t/m³ (about 1.1 US tons per yd³) · Bags = ⌈V ÷ bag volume⌉Screened topsoil weighs roughly 1.2–1.4 tonnes per cubic metre when dry and more when wet. A bulk bag holds about 0.75 m³ (≈ 1 tonne).
Worked examples
- 2.4 × 1.2 × 0.3 = 0.864 m³ + 10% = 0.95 m³
- ≈ 1.24 tonnes = 24 × 40 L bags, or 2 bulk bags
- 8 × 4 × 1 = 32 ft³ + 10% = 35.2 ft³ = 1.30 yd³
- = 18 × 2 ft³ bags
Recommended soil depths
| Use | Depth |
|---|---|
| Top-dressing a lawn | 0.5–2 cm (¼–¾ in) |
| Under new turf or seed | 10–15 cm (4–6 in) |
| Flower borders | 20–30 cm (8–12 in) |
| Vegetable raised beds | 30–45 cm (12–18 in) |
| Shrubs and small trees | 45–60 cm (18–24 in) |
A good raised bed mix
A common recipe is roughly 60% screened topsoil, 30% compost and 10% grit or perlite for drainage. In deep beds you can fill the bottom third with logs, branches or rough soil to save buying as much bagged mix.
Frequently asked questions
How much soil do I need for a raised bed?
Multiply length × width × depth. A 2.4 × 1.2 m bed 30 cm deep holds 0.86 m³, about 0.95 m³ after allowing for settling.
How many bags of soil in a cubic metre?
25 bags of 40 litres, 20 bags of 50 litres or about 1.3 bulk bags.
How many cubic feet in a yard of soil?
27 cubic feet. A cubic yard of topsoil weighs about 1 to 1.2 US tons.
Related calculators
Results are estimates. Soil density varies with moisture and composition; check with your supplier.