How the topsoil calculator works
Topsoil is ordered by volume, often priced and delivered by weight, and it sinks after it is spread. The calculator takes the area (length × width), multiplies it by the finished depth, adds a settling allowance, then converts that volume into a weight using the bulk density of the soil you choose.
Volume = length × width × depth ÷ (1 − settling %) · Weight = volume × densityScreened soil tipped off a lorry is full of air. Once it is raked, rolled and watered it typically loses 10–20% of its height, so 15% is the default. Because the loss is a share of the loose height, the calculator divides by 0.85 rather than adding 15%: 10 cm plus 15% is 11.5 cm, which settles to only 9.8 cm, while 10 ÷ 0.85 = 11.8 cm settles to the full 10 cm. Density runs from about 1.2 t/m³ for dry screened loam to 1.6 t/m³ or more for wet, clay-rich soil. In US terms, one cubic yard of average moist topsoil weighs about 2,360 lb, a little under 1.2 US tons.
Worked example
A new lawn area of 6 m × 4 m needs 10 cm of soil. 24 m² × 0.10 m = 2.4 m³, and with 15% for settling 2.4 ÷ 0.85 = 2.82 m³, spread 11.8 cm deep. At 1.4 t/m³ that weighs roughly 3.95 tonnes – 71 bags of 40 L, which nobody wants to carry. Three 1 m³ bulk bags, or one loose tipper load, is the sensible order. The imperial equivalent: 20 ft × 13 ft at 4 inches is 86.7 ft³, 102 ft³ after settling, which is 3.78 cubic yards and about 4.5 US tons.
Recommended depths
| Job | Depth of topsoil | Notes |
|---|---|---|
| Top-dressing an existing lawn | 0.5–1 cm (¼–½ in) | Sieved soil or soil–sand mix, brushed into the sward |
| New lawn from seed or turf | 10–15 cm (4–6 in) | Over loosened subsoil |
| Flower and shrub beds | 15–20 cm (6–8 in) | Blend in compost |
| Vegetable beds | 20–30 cm (8–12 in) | Room for carrots, parsnips and potatoes |
| Raised beds | Full bed height | The bottom third can be cheaper subsoil |
Density and weight
| Soil condition | Metric | Imperial |
|---|---|---|
| Dry, screened | 1.2 t/m³ | about 2,020 lb/yd³ |
| Average moist | 1.4 t/m³ | about 2,360 lb/yd³ |
| Wet or clay-rich | 1.6 t/m³ | about 2,700 lb/yd³ |
Retail bags are usually 20–40 L in Europe and 0.75 or 1 cu ft in the US; bulk bags hold 0.7–1 m³ or about 1 cubic yard. Bagged products are often lighter than yard soil because they contain more organic matter.
Buying and spreading tips
- Respect payload limits. A car trailer rated for 750 kg carries barely half a cubic metre of moist soil, and one cubic yard (around 2,400 lb) exceeds the payload of many half-ton pickups.
- Ask for screened soil. Unscreened loads contain stones, roots and clods that ruin a level lawn surface.
- Loosen the ground underneath. Spreading loam over compacted clay creates a wet layer at the junction. Fork or rotavate the subsoil first so water and roots pass through.
- Keep it off tree roots. Raising the level by more than about 5 cm over a tree's root zone can suffocate the roots.
- Order in one go. Soil from different batches can differ in colour, texture and stone content, which shows on a lawn.
Frequently asked questions
How much does a cubic yard of topsoil weigh?
Between about 2,000 and 2,700 lb depending on moisture. Average moist loam is around 2,360 lb, just under 1.2 US tons.
How many bags of topsoil make a cubic yard?
A cubic yard is 27 ft³, so it takes 27 bags of 1 cu ft or 36 bags of 0.75 cu ft.
How much topsoil do I need for a 1,000 sq ft lawn?
At 4 inches deep, 1,000 ft² needs 333 ft³, or 12.3 cubic yards once settled. Allowing for 15% loss of height (12.3 ÷ 0.85), order about 14.5 cubic yards.
How many tonnes is a cubic metre of topsoil?
Between 1.2 and 1.6 tonnes, typically 1.4 t when moist. A bulk bag sold as one tonne therefore holds only about 0.7 m³.
What is the difference between topsoil and compost?
Topsoil is mineral soil – sand, silt and clay – with some organic matter; compost is decomposed organic material. For beds, blend topsoil with 20–30% compost; for lawns use plain screened topsoil.
Last reviewed: 2026-09-27 · How we calculate