How much does topsoil weigh per m³?

Screened topsoil typically weighs around 1.4 tonnes per cubic metre, though this can vary between 1.3-1.5 tonnes depending on moisture content and composition. Wet topsoil can weigh significantly more. This topsoil quantity calculator uses 1.4 tonnes per m³ as the standard UK trade density for screened topsoil.

How deep should I lay topsoil for a new lawn?

For a new lawn, you should aim for a minimum of 150mm (6 inches) of topsoil. For best results, 200-300mm is recommended. If you are laying turf, 100-150mm may suffice over existing reasonable soil — use our Turf Calculator (/landscaping/turf-calculator) to work out how many rolls you need. For flower beds and raised beds, 300mm or deeper is ideal — see our Raised Bed Soil Calculator (/landscaping/raised-bed-soil-calculator).

How much topsoil is in a bulk bag?

A standard bulk bag (also called a tonne bag or dumpy bag) contains approximately 0.75 m³ of topsoil, which weighs roughly 1 tonne. However, actual weight can vary — most suppliers fill bags to around 850-1000kg. Always check with your specific supplier. This topsoil tonnage calculator converts volume to bulk bags automatically.

What is the difference between topsoil and subsoil?

Topsoil is the uppermost layer of soil (typically 150-300mm deep) that contains organic matter and nutrients essential for plant growth. Subsoil sits below and is less fertile with fewer nutrients. For any planting or lawn work, you should always use proper screened topsoil, ideally BS 3882 certified.

Should I buy topsoil by the tonne or bulk bag?

Bulk bags (approx. 0.75 m³) are convenient for smaller projects and can be placed precisely where needed. For larger areas, buying loose topsoil by the tonne is more cost-effective — typically 30-50% cheaper per tonne. Most UK suppliers deliver loose topsoil in tipper lorries for orders over 10 tonnes. If you need gravel or sub-base too, see our Gravel Calculator (/landscaping/gravel-calculator) and Type 1 Sub-Base Calculator (/landscaping/type-1-sub-base-calculator).

TradeCalcs

Topsoil Calculator — How Much Topsoil Do I Need?

Calculate how many tonnes or bulk bags of topsoil you need for your garden, lawn or landscaping project. Uses standard UK topsoil density.

Area Length

Length of the area to cover

Area Width

Width of the area to cover

Depth

150mm standard for new lawns

Include wastage allowance

Adds 10% extra for settlement and spreading losses

Wastage Percentage

10% recommended for most projects

Price Per Tonne (optional)

Enter your supplier price for a cost estimate

How We Calculate This

Our topsoil calculator works by multiplying your area dimensions by the required depth to get the total volume in cubic metres, then converting to weight using the standard density of screened topsoil.

The formula

Volume (m³) = Length (m) × Width (m) × Depth (m)

Weight (tonnes) = Volume (m³) × 1.4

Bulk bags = Volume (m³) ÷ 0.75 (rounded up)

Key assumptions

Topsoil density: 1.4 tonnes per m³ (standard screened topsoil)
Bulk bag volume: 0.75 m³ per bag (industry standard)
Default depth: 150mm — suitable for new lawns and general landscaping
Wastage: 10% recommended to account for settlement and spreading losses

Topsoil quality should conform to BS 3882:2015 for landscaping use. Always order screened topsoil for lawn and garden projects — unscreened topsoil may contain stones, roots and debris.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates. Verify with your supplier.