About this Self-Leveling Compound Calculator
Calculate self-leveling compound bags from floor area, average fill depth and the coverage printed on the chosen product data sheet. A bag covering a stated area at 3 mm will not cover that same area at 10 mm. Both coverage and its reference thickness are required.
Use an area-weighted average depth obtained from a floor survey. The deepest low spot alone overstates the requirement across the room, while a simple average of unevenly spaced survey readings can understate or overstate it.
Measurements and information you need
Divide the floor into surveyed zones. Multiply each zone area by its average fill depth, add the zone volumes and divide by total area to find the area-weighted depth. Replace the hypothetical default coverage of 2 m² at 10 mm with the current product coverage and matching reference thickness. These defaults do not identify a manufacturer or bag size.
- Floor area: enter the measured or manufacturer-specified value in the unit shown beside the field.
- Area-weighted average fill depth: enter the measured or manufacturer-specified value in the unit shown beside the field.
- Manufacturer coverage per bag at reference depth: enter the measured or manufacturer-specified value in the unit shown beside the field.
- Reference depth for stated coverage: enter the measured or manufacturer-specified value in the unit shown beside the field.
Formula and calculation method
Manufacturer coverage applies at a particular thickness. The tool scales that coverage by the ratio between average installed depth and reference depth, adds waste, then rounds upward. Defaults are hypothetical and must be replaced with current product data.
Worked metric example: Floor area: 24 m²; Area-weighted average fill depth: 10 mm; Manufacturer coverage per bag at reference depth: 2 m²; Reference depth for stated coverage: 10 mm. With a 10% allowance where applicable, the net result is 12 bags and the final result is 14 bags. Purchase summary: 14 bags · 264 L placed volume including allowance.
How to use the calculator
- Survey the floor against the intended finished level and divide uneven areas into zones.
- Calculate total area and its area-weighted average fill depth.
- Read bag coverage and its matching reference depth from the same product data sheet.
- Enter an allowance for substrate variation and material loss, then calculate whole bags.
- Check minimum lift, maximum lift, primer, substrate suitability, moisture and curing requirements before installation.
How to read the result
In this metric example the result is expressed in bags. Base quantity is the net calculated requirement, rounded up for whole-package results. Waste allowance is the extra quantity added where the calculation supports it. The selected unit system determines the result unit shown in the tool.
In this metric example the result is expressed in bags. Base quantity is the net calculated requirement, rounded up for whole-package results. Waste allowance is the extra quantity added where the calculation supports it. The selected unit system determines the result unit shown in the tool.
In this metric example the result is expressed in bags. Base quantity is the net calculated requirement, rounded up for whole-package results. Waste allowance is the extra quantity added where the calculation supports it. The selected unit system determines the result unit shown in the tool.
In this metric example the result is expressed in bags. Base quantity is the net calculated requirement, rounded up for whole-package results. Waste allowance is the extra quantity added where the calculation supports it. The selected unit system determines the result unit shown in the tool.
In this metric example the result is expressed in bags. Base quantity is the net calculated requirement, rounded up for whole-package results. Waste allowance is the extra quantity added where the calculation supports it. The selected unit system determines the result unit shown in the tool.
In this metric example the result is expressed in bags. Base quantity is the net calculated requirement, rounded up for whole-package results. Waste allowance is the extra quantity added where the calculation supports it. The selected unit system determines the result unit shown in the tool.
In this metric example the result is expressed in bags. Base quantity is the net calculated requirement, rounded up for whole-package results. Waste allowance is the extra quantity added where the calculation supports it. The selected unit system determines the result unit shown in the tool.
The result is whole bags, not loose powder volume. The secondary summary also shows placed fill volume, including allowance. Bags are based on the entered coverage, not a generic powder density.
If a hypothetical bag covers 2 m² at 10 mm, a 24 m² floor at 5 mm needs 6 bags before allowance. At 10 mm it needs 12; at 20 mm it needs 24. With 10% waste these orders become 7, 14 and 27 bags respectively.
Choosing a waste allowance
Apply an allowance after calculating net bag demand. Do not increase mixing water to improve apparent coverage; water ratios and preparation must follow the product data sheet. Primer and aggregate-extension systems are separate takeoffs.
Common mistakes to avoid
- Using the deepest depression as the average depth for the entire floor.
- Entering bag coverage without its matching reference thickness.
- Using dry powder density or added water to infer installed yield.
- Exceeding a product lift limit because the average depth appears acceptable.
Flooring planning notes
Use the finished floor outline, split irregular rooms into simple rectangles and consider layout direction. Pattern matching, narrow edge cuts, damaged pieces and future repairs can increase the order.
Check before ordering or building
- Use an area-weighted average from a floor survey, not just the deepest depression.
- Check minimum and maximum lift thickness, substrate, primer and moisture requirements.
- Do not use dry powder density or extra mixing water to infer yield; use the chosen product coverage chart.
Measure critical dimensions at least twice and keep a written record of the assumptions used. Compare the calculated requirement with current manufacturer literature, local code and the supplier’s package or delivery increments.
Frequently asked questions
How do I calculate bags of self-leveling compound?
Divide floor area by the bag coverage, multiply by average depth divided by the coverage reference depth, then add an allowance and round upward.
How do I average an uneven floor?
Use area-weighted zones: sum area times depth for every zone, then divide that total by total area. A 10 m² zone at 4 mm and a 2 m² zone at 10 mm have a weighted average of 5 mm, not 7 mm.
Can I use any self-leveling product?
Only when its specified coverage is appropriate to the chosen installation. Follow the data sheet for thickness limits and any aggregate extension; linear coverage scaling is not a substitute for a product-specific installation system.
Technical basis and references
Geometry is calculated in SI internally and converted only for display. Length, area and volume conversions use exact NIST conversion factors. Product yield, density and coverage values remain editable because they vary by manufacturer, formulation and market.