Self-Levelling Compound Calculator — How Much Do I Need?
Work out how much self-levelling compound you need in seconds. Enter your floor area and the average depth you want to level, and we'll calculate the number of 20kg bags of Larsen SLC1550 required — including 10% for wastage.
Which compound do I need?
How the Calculation Works
A 20kg bag of Larsen SLC1550 covers approximately 1m² at 10mm depth. The formula: bags = floor area (m²) × average depth (mm) ÷ 10, plus 10% for wastage and uneven spots. Example: a 20m² kitchen levelled at an average 5mm needs 20 × 5 ÷ 10 = 10 bags, so order 11.
How much does a 20kg bag of self-levelling compound cover?
Based on Larsen SLC1550 at about 1m² per 20kg bag at 10mm. Bags for 10m² include 10% wastage, rounded up.
| Average depth | Coverage per 20kg bag | Bags for 10m² |
|---|---|---|
| 3mm | about 3.3m² | 4 |
| 5mm | about 2m² | 6 |
| 10mm | about 1m² | 11 |
| 15mm | about 0.67m² | 17 |
| 20mm | about 0.5m² | 22 |
For 20 or more bags, the 24-bag pallet works out the same price per bag, and the 48-bag pallet qualifies for Free UK delivery over £499.
How many bags of self-levelling compound do I need?
Multiply the floor area in m² by the average depth in mm and divide by 10, then add 10% for wastage. A 20m² room at 5mm needs 10 bags, so order 11. Or use the calculator above.
Can I go thinner than 3mm?
SLC1550 is designed for 3–50mm in one pour. For a skim under 3mm, ask our Coventry team on 0330 520 1804 which product suits your floor.
Tips Before You Pour
Measure depth at several points and use the average — floors are rarely evenly out. Always prime the substrate first, and for timber floors use a flexible fibre-reinforced compound like SLC1550 or a two-part latex leveller. SLC1550 takes light foot traffic in 2–4 hours and can usually be tiled or overlaid after 1–3 days depending on depth and conditions.
Ready to Order?
Shop the full self-levelling compound range, grab a pallet deal for bigger jobs, or call our Coventry team on 0330 520 1804 for advice. Levelling floors for several jobs a month? Use our trade enquiry form.