Floor levelling compound Calculator: measuring notes and method
Build an average from measured depths
Take level readings across the floor and divide it into areas with similar fill depths. A single deepest reading applied to the entire floor can substantially overestimate material.
Convert the product consumption correctly
At an illustrative consumption of 1.7 kg/m² per mm, 20 m² at 5 mm average depth needs 170 kg before allowance. That rounds up to nine 20 kg bags.
Formula
Mass = area × applied thickness × density × (1 + waste ÷ 100). Bags = mass ÷ bag size, rounded up.
Worked examples in metric and imperial units
Illustrative values match Reset example and stay fixed when you edit the calculator. Both columns describe the same calculation; converted inputs are rounded.
Metric worked example
- Total surface area
- 24 m²
- Average fill depth
- 5 mm
- Material mass per applied m³
- 1,700 kg/m³
- Bag size
- 20 kg
- Waste allowance
- 10 %
Bags to buy: 12
Imperial worked example
- Total surface area
- 258.3339 ft²
- Average fill depth
- 0.1969 in
- Material mass per applied m³
- 106.1275 lb/ft³
- Bag size
- 44.0925 lb
- Waste allowance
- 10 %
Bags to buy: 12
Follow the calculation
Lengths in this working are in metres.
- Applied volume including allowance = 24 × 0.005 × 1.1 = 0.132 m³.
- Material mass = 0.132 × 1,700 = 224.4 kg.
- Divide by 20 kg per bag and round up.
Reviewed 19 October 2026. How calculations are checked · Report a correction