About this calculator
Self-leveling underlayment or a sand-mix mortar bed to flatten a floor before tile, vinyl or wood.
How it’s calculated
Volume = area × average depth. Self-leveller is taken at about 1.7 kg per m² per mm, so a 50 lb bag covers about 45 sq ft at ⅛". Screed uses a dry-volume factor of 1.33.
Worked example
With these inputs:
- Measure by
- Length × width
- Length
- 15 ft
- Width
- 12 ft
- Average depth
- 0.25 in
- Material
- Self-leveling underlayment (50 lb)
- Waste allowance
- 10%
the result is:
- Bags needed
- 9 bags
- Volume
- 4.1 cu ft
- Area
- 180 sq ft
Tips from the trade
- Measure depth on a grid with a straightedge and average it. Don’t guess.
- Prime the substrate, and seal gaps and drains so the leveller doesn’t run away.
- Thick pours may need a deep-fill product or aggregate added.
Results are estimates for planning and pricing. Check quantities against your drawings, the manufacturer’s data and local building codes before ordering.