Lawn area (add up to 3 areas if your lawn isn't one simple rectangle)
Turf rolls
| Area | Amount |
|---|
Topsoil top-up (leave depth at 0 to skip)
| Topsoil needed | 0.00 t |
| Bulk bags | 0 |
| 25kg bags | 0 |
How this calculator works
Each lawn area is a simple length × width rectangle; enter up to three if your lawn is an L-shape or has a separate patch, and the total area is the sum of all three. Turf rolls are sold in a range of sizes depending on the supplier, so the roll size field is editable rather than fixed; UK rolls commonly run from about 0.6 to 1 m2 each, check the size quoted by your turf supplier and enter it here for an accurate roll count. Wastage covers trimming to fit awkward edges and curves, and the odd damaged roll.
Do you need a topsoil top-up?
New turf roots into whatever is underneath it, so if the existing ground is compacted, uneven, or low in organic matter, a layer of fresh topsoil first gives the turf a much better start. A 25 to 50mm top-up is typical where the ground just needs levelling and enriching; deeper layers are for building up a new bed from scratch. Leave the depth at 0 if your existing soil is already in good condition and just needs raking level.
How much topsoil do you need for turf?
For a brand new lawn built up from bare or stripped ground, rather than a levelling top-up, trade guidance is a topsoil bed of 100 to 150mm deep - deep enough for the turf's roots to establish properly rather than just sitting on the surface. Enter that depth into the "Topsoil top-up" fields above and the tonnes, bulk bags and 25kg bags needed are worked out from the same lawn area you've already entered. For a fuller explanation of depth, tonnes and bulk-bag planning, read the topsoil for turf guide.
Worked example: a 6m × 4m lawn (24 m2, the default in the
fields above) at 120mm depth and the default 1.4 t/m3 topsoil density
needs 24 × 0.12 × 1.4 = 4.03 tonnes - 5 bulk bags, or
162 standard 25kg bags.
Topsoil needed by lawn area (at 1.4 t/m3 density)
| Lawn area | 100mm depth | 150mm depth |
|---|---|---|
| 10 m2 | 1.40 t · 2 bulk bags | 2.10 t · 3 bulk bags |
| 20 m2 | 2.80 t · 4 bulk bags | 4.20 t · 5 bulk bags |
| 30 m2 | 4.20 t · 5 bulk bags | 6.30 t · 8 bulk bags |
| 50 m2 | 7.00 t · 9 bulk bags | 10.50 t · 13 bulk bags |
| 100 m2 | 14.00 t · 17 bulk bags | 21.00 t · 25 bulk bags |
What this calculator does not check
This tool covers turf and topsoil quantities only. It doesn't check drainage (a lawn that regularly waterlogs needs the underlying issue fixed before turfing, not just more soil), existing weed or root removal, or how soon after laying the turf can be walked on or first mowed, which varies by season and turf type. Check with your turf supplier for aftercare specific to the variety you buy.
Related tools
Buying topsoil for raised beds or general levelling rather than just a lawn top-up? The topsoil calculator includes dedicated presets and 25L bag counts. For gravel, sand or hardcore in bulk, the aggregate calculator handles larger volumes and other materials.
FAQ: topsoil for turf and grass
How much topsoil do I need for turf? It depends on your starting ground: 25 to 50mm to level and enrich reasonable existing soil, or 100 to 150mm if you're building a full topsoil bed for a new lawn from bare ground. Enter your lawn area and chosen depth into the calculator above for tonnes and bulk bags.
How much topsoil for grass seed rather than turf? The same 100 to 150mm bed depth applies when seeding a new lawn from bare ground - seed and turf both need proper root depth to establish. Overseeding an existing lawn to thicken it up generally needs no topsoil at all, beyond filling the odd bare patch.
Is this a topsoil calculator too, not just turf? Yes - the "Topsoil top-up" card above works out tonnes, bulk bags and 25kg bags from any area and depth you enter, independently of the turf roll count.