Floor Leveling Compound Calculator
Enter your floor area and desired pour thickness to find out exactly how many bags of self-leveling compound to buy, scaled from your bag's own printed coverage chart.
Both printed on the bag's coverage chart.
How this is calculated
One square meter covered to a 1mm thickness is exactly one liter of mixed compound, so area × thickness already gives the volume you need with no extra conversion factor — the same logic applies with square feet and inches once converted to a common basis internally.
A bag's printed coverage (for example '20kg covers 4m² at 3mm') is only valid at that exact reference thickness — coverage isn't a fixed area per bag, it scales inversely with how thick you actually pour it. This calculator converts the bag's printed area-and-thickness into the volume that bag actually yields, then divides your required volume by that figure — the same depth-scaling approach used for blown-in insulation coverage, and for the same reason: skipping this step is the most common way online leveling-compound calculators get bag counts wrong.
The result is rounded up to the nearest whole bag, since compound is sold by the bag, and the calculator also shows how much mixed volume you'll have left over.
Frequently asked questions
Is this the same as a 'screed calculator'?
Yes — 'screed' is the term more commonly used in the UK and Europe, while 'self-leveling compound' or 'floor leveling compound' is the more common US term for the same type of product and the same calculation.
Why do I need more bags for a thicker pour, not just proportionally more?
Because a bag's printed coverage area is only valid at its printed reference thickness. Pouring thicker than that reference means each bag covers less floor area, so bags-per-square-meter rises faster than thickness alone would suggest if you just scaled the printed area number directly.
Where do I find my bag's coverage numbers?
On the coverage chart printed on the bag, usually showing area covered at one or more reference thicknesses (e.g. '4m² at 3mm' or '2m² at 6mm'). Enter any one row from that chart — the calculator scales correctly from it either way.
Do I need a primer before pouring self-leveling compound?
Most manufacturers recommend a primer coat on the subfloor before pouring, to stop the compound from drying too fast at the edges and to improve adhesion — check your specific product's instructions, since primer requirements vary by subfloor type.
Sources
- Manufacturer coverage-chart methodology for self-leveling compound (depth-scaled bag coverage) — same approach as this site's insulation calculator
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Disclaimer
This tool provides an estimate for informational purposes. Always check your specific product's packaging for its exact coverage chart, and buy a small margin extra for an uneven subfloor that needs more compound in low spots.
Last updated 2026-11-05.