How much does a cubic metre of topsoil weigh?

Approximately 1.4 tonnes (1,400 kg). This varies with moisture content - wet topsoil can weigh up to 1.7 tonnes per m³.

How much does a bulk bag weigh?

A standard builders-merchant bulk bag holds about 0.85 m³. Weight depends on the material — at that volume gravel works out around 1.4–1.5 tonnes, MOT Type 1 around 1.8 tonnes, topsoil around 1.2 tonnes and compost around 0.45 tonnes. Adjust the bulk-bag volume in the advanced options if your supplier uses 0.5–0.6 m³ bags.

Why does weight matter for ordering?

Many suppliers sell aggregates by weight (tonnes) but quote your project in volume (cubic metres), or vice versa. Knowing the density lets you convert between the two so you order the right amount and can check it fits your access and delivery limits.

Do I need to worry about vehicle weight limits?

Yes — even 1 m³ of gravel or MOT Type 1 is well over a tonne. A standard pickup carries roughly 0.5–1 tonne, a single-axle trailer about 0.75 tonnes, and tipper lorries 10–20 tonnes, so a single cubic metre of dense aggregate can exceed a small trailer or van payload.

Why does the same volume of different materials weigh differently?

Density varies hugely. Per cubic metre, MOT Type 1 is about 2,100 kg, gravel 1,700–1,800 kg, sand 1,500–1,600 kg, topsoil about 1,400 kg, compost about 550 kg and bark mulch about 350 kg. Always check weight when ordering loose delivery.

GardenCalcs

Material Weight Calculator — Volume to Weight Conversion

Convert between volume and weight for common garden materials.

MaterialPick the material — the loose bulk density (t/m³) used for the conversion is shown next to each option.

ConvertChoose Volume to Weight (m³ → tonnes) or Weight to Volume (tonnes → m³).

Volume

Volume of material to convert (m³). Area × depth — e.g. 10 m² at 50 mm = 0.5 m³.

How We Calculate This

Weight (tonnes) = Volume (m³) × Density (tonnes/m³). Volume = Weight ÷ Density.

Densities are approximate for loose, dry materials. Wet or compacted materials will be heavier — use the moisture allowance to add weight without changing the volume.

Bulk bags assume a standard 0.85 m³ (850 L) builders-merchant bag; change this in the advanced options if your supplier uses 0.5–0.6 m³ bags. Adding a delivery wastage allowance increases the order volume, so the headline bulk-bag count rises to match.

Frequently Asked Questions

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Last updated: February 2026

All calculations are estimates based on standard gardening guidelines. Results may vary with soil conditions, climate, and plant varieties.