Topsoil and Bark: How Much Do I Need for My Garden? (UK)

A 5 × 4 m lawn topped up with 100 mm of topsoil needs 2.2 m³ (44 bags of 50 litres), and a 4 × 3 m border mulched 50 mm deep needs 0.66 m³ of bark (14 bags). The charts give the quantities for other sizes, and show how far a cubic metre goes.

Topsoil by area and depth

With 10% extra for settling, in cubic metres and 50 litre bags:

One cubic metre covers 20 m² at 50 mm, 10 m² at 100 mm, and 6.7 m² at 150 mm. Use the topsoil calculator for any other size or bag.

Bark mulch by area and depth

With 10% extra, in cubic metres and 50 litre bags:

Bark is light and bulky: a cubic metre is 20 bags of 50 litres. Use the bark calculator for your own border or path.

Bags or a bulk delivery?

• Bags are easy to carry and to store, and sensible for under about half a cubic metre.
• A bulk bag or a loose load is much cheaper per cubic metre, but you need somewhere to put it. It will block a drive or a pavement, so plan the delivery, and put down a tarp.
• Work out the delivery charge: a small order can cost more to deliver than the material is worth.

Topsoil: what to check

• Ask for screened topsoil (to BS 3882, if you can). Cheap loads can contain weeds, stones, clay and rubbish.
• Do not bury the base of trees or shrubs, and keep the soil at least 150 mm below the damp-proof course of a house.
• Loosen the ground underneath before you spread it, so that the new soil can knit into the old and roots can get through.
• Let it settle for a week or two before you sow or turf.

Bark: what to check

• Weed the bed first, and keep the bark clear of plant stems.
• Use a bark that suits the job: fine for beds, chunky for paths, and a play-grade bark for play areas.
• Top it up each year or two as it rots down. This feeds the soil, but it also means you need to keep buying it.

Frequently asked questions