How much topsoil do I need before laying turf?
Published · Updated · By Sai Nath
Lay at least 100 mm of turf underlay or topsoil: 0.1 m³ per square metre of lawn. A 10 × 6 m lawn (60 m²) needs 60 × 0.1 = 6 m³, or 9 m³ at 150 mm. Yates says to dig out 130 mm, so 100 mm of underlay plus 30 mm of turf sits flush.
In the app: Soil in MeisterCalc, with a worked example and real screens.
Checked on 5 November 2026. New turf goes down on a bed of soil, sold as turf underlay or topsoil by the cubic metre. The amount is the lawn’s area times the depth of that bed. The depths come from a turf guide by Yates and from Rolawn, a UK turf grower, both linked.
How much topsoil do I need per square metre?
Every 10 mm of depth over one square metre is 0.01 m³, or 10 litres. So:
| Depth of underlay | Per m² of lawn | Lawn 1 m³ covers |
|---|---|---|
| 100 mm | 0.1 m³ (100 L) | 1 ÷ 0.1 = 10 m² |
| 150 mm | 0.15 m³ (150 L) | 1 ÷ 0.15 = 6.7 m² |
Multiply the lawn’s area by the per-m² figure: area × depth in metres = cubic metres to order.
How deep should the soil under turf be?
- Yates’ DIY turf guide says to excavate the top 130 mm, and that “Turf underlay should be at least 100 mm deep, leaving 30 mm for the turf” so the turf sits flush with the existing edges (Yates DIY Turf Guide).
- Rolawn, a UK turf grower, says the soil “should be turned over or cultivated to at least 100mm deep, ideally 150mm” (Rolawn, preparing to lay turf).
So 100 mm is the floor in both, and 150 mm is the deeper option. Rolawn’s figure is for cultivating the soil you have; if that soil is poor and you are bringing new soil in, the depth you import is the one to multiply.
Worked example: a 10 m × 6 m lawn
- Area: 10 × 6 = 60 m².
- Underlay at 100 mm: 60 × 0.1 = 6 m³.
- At 150 mm: 60 × 0.15 = 9 m³.
- With 10% extra for low spots and settling: 6 × 1.1 = 6.6 m³ at 100 mm. Yates suggests ordering a little extra underlay to keep for top-dressing low spots.
How much soil do I dig out?
Yates’ 130 mm dig over the 60 m² lawn is 60 × 0.13 = 7.8 m³ of soil measured in the ground. Dug soil is looser than it was in the ground, so it takes up more room in a skip or trailer than that figure; ask the skip hire firm how they size loads. If the existing soil is good, you may cultivate it rather than replace it, and dig out less.
How much turf do I order?
Turf is sold by the square metre. Yates says to add 5 percent for offcuts: multiply the area by 1.05. For the 60 m² lawn that is 60 × 1.05 = 63 m².
How many tonnes of underlay is that?
Yards usually sell turf underlay by the cubic metre. If one sells by the tonne, ask for its kg per m³ and multiply: tonnes = m³ × kg per m³ ÷ 1,000. Soil weighs more wet than dry, so the figure is the yard’s, not a table’s. The method is in cubic metres to tonnes; to bring it home yourself, see how many cubic metres fit in a trailer.
Is this the same as top-dressing a lawn?
No. Top-dressing spreads a thin layer over an existing lawn, measured in millimetres rather than a 100 mm bed. The sum is the same, area × depth, and a worked top-dress is in how much soil do I need.
What MeisterCalc does and doesn’t do
- Soil gives volume, tonnes and a +10% order in tonnes for the density you enter.
- Concrete ▸ Slab gives cubic metres and litres for a rectangle, free.
- Rectangles only in Soil: split an odd-shaped lawn into rectangles and add them.
- It has no turf counter and no excavation or bulking figure, and it doesn’t know your soil. A turf supplier does.
Try it
Concrete, Stairs and Check Square are free to use, with no trial and no card needed. The other 13, Soil and Gravel included, unlock with a one-time purchase, no subscription required, or with a weekly subscription that starts with a 3-day free trial; Google Play shows the prices in your currency. Calculations work offline on Android 7.0 or later.
Sources
- Yates, DIY Turf Guide (PDF): excavate 130 mm; turf underlay at least 100 mm, leaving 30 mm for the turf; area × 1.05 for offcuts; order a little extra underlay for low spots. Checked on 5 November 2026.
- Rolawn, preparing to lay turf: cultivate at least 100 mm, ideally 150 mm. Checked on 5 November 2026.