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Self-levelling screed calculator
Calculate bags of self-levelling compound and primer for floor preparation under vinyl, LVT, carpet tiles or resin. Use the average depth across the floor, not the thinnest point.
How the calculation works
Self-levelling compounds are sold by the bag, and the data sheet gives consumption in kilograms per square metre per millimetre.
Bags = round up (powder ÷ bag size)
Average depth matters more than anything else on this page. A floor specified at 3 mm can average 5 to 6 mm once you fill dips. Measure with a straightedge or laser before you price.
Typical consumption is 1.5 to 1.8 kg per m² per mm. Fibre-reinforced and deep-fill grades differ, so check the data sheet.
Site tips
- Price floor prep as its own line, not hidden inside the floor finish.
- Quote a depth and add a rate per extra millimetre. This protects you when the slab is worse than expected.
- Pump-applied jobs waste less than hand-mixed ones. Adjust the waste figure to match.
Questions
How many bags of self-levelling compound per m²?
At 5 mm and 1.7 kg/m²/mm you use 8.5 kg per m², so one 25 kg bag covers about 2.9 m².
What depth should I allow under LVT or vinyl?
Most installers allow 3 to 5 mm as a minimum. The finish manufacturer's flatness requirement decides the real figure.
Do I need to prime before self-levelling?
Almost always. Primer controls suction and helps the compound bond. Follow the compound manufacturer's primer and dilution.