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Topsoil calculator

Work out how much topsoil you need for a new lawn, flower beds or a raised bed. You get the amount in tonnes, cubic metres and litres, and the number of bulk bags to order.

Man raking dark topsoil level in a timber raised bed in a back garden
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Loose soil settles after raking and watering, so order a little over.

Your result

Topsoil needed

4.95 tonnes

about 1.5 tonnes per m³. One tonne covers about 4.4 m² at this depth.

Volume
3.3 m³3 m³ plus 10% extra
Litres
3,300 litreshandy for raised beds and bagged topsoil sold by the litre
Bulk bags (850 kg)
6nominal 850 kg each; check the weight on the bag
  • 150 mm is for bare ground. If the soil you have is decent, 100 mm of new topsoil may be enough.
  • Topsoil weight varies with moisture. Damp or packed soil is heavier, so check the delivery note.

Add this to your project shopping list, then print it or take it to the merchant.

Open shopping list

How to use the topsoil calculator

  1. Choose the Shape of the area: a rectangle, circle, triangle, or enter the area if you already know it.
  2. Measure it and enter the sizes. You can mix metres and feet. Each box has its own unit.
  3. Under What is it for? pick new lawn or turf (150 mm), flower beds and borders (200 mm), raised bed or vegetables (300 mm), or enter your own depth.
  4. Leave Extra for settling at 10%. Loose soil sinks after raking and watering, so a little over is safer than a little under.
  5. Read the tonnes for a loose delivery, the litres for bagged topsoil or raised beds, or the bulk bags. Then tap Add to shopping list or Share link.

Why use this calculator

It speaks in the units topsoil is sold in. You get tonnes for a delivery, litres for bags and raised beds, and 850 kg bulk bags, plus how many m² one tonne covers at your depth.

It has depth presets for real jobs. A new lawn, a border and a raised bed need different depths, and you can still type your own.

It is neutral. It is not built to sell you a particular product, and it shows its working so you can check it or take it to a supplier.

How we worked it out

Your numbers, step by step. This updates as you change the calculator.

  1. Area = length × width = 5 m × 4 m = 20 m²
  2. Volume = area × depth = 20 m² × 0.15 m = 3 m³
  3. Add 10% for settling: 3 × 1.1 = 3.3 m³ (3,300 litres)
  4. Weight = 3.3 m³ × about 1.5 t/m³ = 4.95 tonnes
  5. Bulk bags: 4.95 t ÷ 0.85 t per bag = 6 bags

The formula

The volume of topsoil is the area times the depth in metres. We add your settling allowance and then multiply by the weight of soil.

Tonnes = area × depth × (1 + extra) × tonnes per m³

A 5 m by 4 m lawn is 20 m². At 150 mm (0.15 m) deep that is 3 m³. Add 10% and it is 3.3 m³, which is 3,300 litres. At about 1.5 tonnes per m³ it weighs 4.95 tonnes.

  • Litres: m³ × 1,000.
  • Bulk bags: tonnes ÷ 0.85, rounded up. For 4.95 tonnes that is 6 bags.
  • Cover per tonne: 1 ÷ (depth × tonnes per m³). At 150 mm that is 1 ÷ (0.15 × 1.5) = 4.4 m².

What we assume

  • Screened topsoil weighs about 1.5 tonnes per m³ as delivered. Some suppliers quote about 1.3 for screened soil and up to 1.7 when it is damp or packed. We use 1.5 so you do not under-order.
  • Depths: 150 mm for a new lawn on bare ground (100 mm if the soil is decent), 200 mm for flower beds and borders, and 300 mm for raised beds and vegetables. Rolawn suggests 150 to 200 mm for general planting and 300 to 400 mm for root crops.
  • A bulk bag is taken as 850 kg. Real bags vary, and some are nearer 950 kg, so check the weight on the bag.
  • 10% extra for settling is our default. It is not a fixed rule.

Tips

  • Dig a small test hole to see how much good soil you already have. If it is decent, 100 mm of new topsoil on a lawn may be enough instead of 150 mm.
  • Order by weight, but check the delivery note. Topsoil is heavier when it is damp or packed, so a tonne of wet soil is less soil than a tonne of dry.
  • Rake the area level before you measure, and check the depth in a few places. A small dip in the ground takes a surprising amount of soil.
  • Laying turf? Tick the box in the turf calculator to work out the topsoil underneath at the same time.
  • For a raised bed, work in litres. Multiply length by width by depth in metres, then by 1,000, and compare it with the litres on the bag.

FAQs

How much topsoil do I need for a lawn?
About 0.23 tonnes per m² at 150 mm deep, or 0.25 tonnes with 10% extra. A 5 m by 4 m lawn needs about 5 tonnes, which is 6 bulk bags of 850 kg.
How many m² does 1 tonne of topsoil cover?
About 4.4 m² at 150 mm deep, 3.3 m² at 200 mm, and 2.2 m² at 300 mm. That uses a weight of about 1.5 tonnes per m³.
How many bulk bags of topsoil do I need?
Divide your tonnes by 0.85 and round up. For example, 5 tonnes is 6 bags. A bulk bag of topsoil holds roughly 0.6 m³ and covers about 4 m² at 150 mm.
How deep should topsoil be for a new lawn or turf?
150 mm on bare ground, or 100 mm if the soil already there is decent. Flower beds and borders usually get 200 mm, and raised beds or vegetables about 300 mm.
How many litres of topsoil do I need for a raised bed?
Work out length × width × depth in metres, multiply by 1,000, and add 10%. A 2.4 m by 1.2 m bed filled to 300 mm needs about 950 litres. The calculator shows litres directly.
How many cubic metres is a tonne of topsoil?
About 0.67 m³, because screened topsoil weighs about 1.5 tonnes per m³. Some suppliers say 1.3 tonnes per m³, and damp or packed soil can be heavier, so the figure moves.
How much extra topsoil should I order for settling?
10% is a safe default for loose soil, because it settles when you rake and water it. Use less if the soil is already firm, and more for a deep fill.

Last reviewed: 6 November 2026 · How we calculate · Report an error