Self Levelling Compound Calculator
Calculate exactly how many bags of self levelling compound you need for any floor area and pour depth. Get material volume, bag count, waste allowance, and estimated cost — instantly.
Floor Levelling Compound Estimator
Enter your floor dimensions and pour depth to calculate bags needed
Typical pours are 2–6mm. Most products max out at 10mm per pour. Use the common depths below.
Coverage varies by product. Check your bag’s technical data sheet for exact figures.
A 10% waste allowance is recommended for standard rooms. Increase to 15% for complex shapes.
Compound Estimate
Bags of self levelling compound required
Enter your floor dimensions and pour depth, then click Calculate Bags Needed to see your material estimate.
Coverage Guide by Depth & Area
How many 20kg bags of self levelling compound are needed for common room sizes at different pour depths. Based on standard coverage of 3.3 m² per bag at 3mm depth with a 10% waste allowance.
| Room / Area | Floor Area | At 3mm depth | At 5mm depth | At 8mm depth |
|---|---|---|---|---|
| Small Hallway | 5 m² | 2 bags | 3 bags | 5 bags |
| Bathroom / WC | 7 m² | 3 bags | 4 bags | 7 bags |
| Kitchen | 10 m² | 4 bags | 6 bags | 10 bags |
| Average Bedroom | 14 m² | 6 bags | 9 bags | 14 bags |
| Large Lounge | 20 m² | 8 bags | 12 bags | 20 bags |
| Open Plan Kitchen/Diner | 30 m² | 11 bags | 17 bags | 27 bags |
| Large Open Plan | 50 m² | 19 bags | 29 bags | 46 bags |
Self Levelling Compound FAQ
Everything you need to know about calculating, mixing, and applying self levelling compound for UK floor projects.
The amount of self levelling compound you need depends on the floor area and the depth of pour. A standard 20kg bag typically covers approximately 3 to 4 square metres at a 3mm depth. To calculate bags needed: multiply your floor area (m²) by your pour depth (mm), then divide by 1000 to get volume in litres, and divide by the coverage per bag stated by the manufacturer.
Most standard self levelling compounds have a minimum pour depth of 2mm and a maximum of around 10mm in a single pour. For deeper corrections beyond 10mm, you should use a floor levelling screed or pour multiple layers, allowing each layer to fully cure (typically 24 hours) before applying the next. Some specialist deep-fill products allow pours up to 50mm or more.
Self levelling compound typically becomes walkable within 2 to 4 hours at normal room temperature (20°C). It is usually ready for light floor coverings such as vinyl or carpet within 24 hours. For ceramic tiles or heavy floor coverings, allow at least 24 to 48 hours. Full cure for heavy loads takes up to 28 days. Cold temperatures, high humidity, or thick pours will significantly extend drying times.
Yes, priming is essential before applying self levelling compound on most substrates. Primer seals the surface, reduces suction, improves adhesion, and prevents air bubbles. Concrete and cement screeds require a diluted SBR or dedicated primer. Plywood and timber floors need a flexible adhesion primer. Failing to prime can result in the compound drying too quickly, cracking, or losing adhesion to the substrate.
Self levelling compound can be applied over ceramic tiles, provided they are firmly bonded, clean, and free from any grease or contamination. Loose or hollow-sounding tiles must be re-fixed or removed first. Existing vinyl, carpet, or wooden floor coverings should generally be removed before application, as they may be too flexible or absorbent to support the compound properly.
Self levelling compound should be mixed by adding the powder to the correct amount of clean, cold water (as specified by the manufacturer — typically 4 to 5 litres per 20kg bag). Use a slow-speed electric drill with a paddle mixer for 2 to 3 minutes until a smooth, lump-free consistency is achieved. Do not add excess water, as this weakens the compound and causes cracking. Work in small batches and pour within 5 to 10 minutes of mixing.
A 20kg bag of self levelling compound typically covers approximately 3.3 square metres at 3mm depth, 2.5 square metres at 4mm, or 1.65 square metres at 6mm. Coverage varies between products and manufacturers, so always check the technical data sheet for the specific product you are using. Add a 10% waste allowance to your calculated quantity.
Self levelling compound can be used on timber and plywood floors, but extra preparation is required. The boards must be firmly fixed with screws to prevent movement. All gaps and knot holes should be filled. A flexible primer must be applied to seal the timber and improve adhesion. Use a flexible self levelling compound formulated for timber substrates, as standard rigid compounds may crack due to natural timber movement.