How Much Topsoil for a Garden?

How We Calculated This

Topsoil is calculated by volume and then converted to weight for ordering:

Area: 10m x 5m = 50m²
Depth: 150mm = 0.15m
Volume: 50 x 0.15 = 7.5m³
Weight: 7.5 x 1.4 = 10.5 tonnes

Why 150mm?

150mm (6 inches) is the standard depth for establishing a new lawn or garden bed. This gives enough depth for grass roots to establish and most garden plants to thrive. For deeper-rooted plants, shrubs, and vegetable gardens, you may want 200–300mm.

Typical Depths for Different Uses

New lawn (turf): 100–150mm
New lawn (seed): 150mm
Flower beds: 200–300mm
Vegetable gardens: 300mm+
Raised beds (topping up): varies

Topsoil Grades

Topsoil quality varies enormously. For garden use, always specify BS 3882 screened topsoil. This is the British Standard for topsoil and ensures it is free from large stones, roots, and contaminants.

Economy/as-dug: Unscreened, may contain stones and roots. Cheapest option for bulk filling.
Screened (10mm): Cleaned and graded. Good for lawns and general garden use.
Premium/blended: Screened and mixed with compost. Best for borders and vegetable growing.

Buying Guide

Bulk bags (850kg–1 tonne): You would need 11 bulk bags. Practical for medium gardens with access.
Loose/tipped: For 10.5 tonnes, tipped delivery is the most economical. Requires good vehicle access and space to tip.
25kg bags: You would need 420 bags — completely impractical at this volume.

Settlement Allowance

Freshly laid topsoil settles by approximately 10–15% over the first few weeks. If you need exactly 150mm of finished depth, order 10–15% extra: 7.5 x 1.1 = 8.25m³, or about 11.5 tonnes.

Tips

Prepare the sub-soil first by breaking up any compacted ground with a rotavator or fork. This helps drainage and root penetration. Rake the topsoil level and allow it to settle for at least 2 weeks before turfing. If seeding, you can sow immediately after raking.