Self-Levelling Compound Calculator UK
Work out how many bags of self-levelling compound you need for your floor. Enter the area, pour depth and coverage rate from your product data sheet to get an accurate bag count.
Enter your floor details
Total area to be levelled
Typical: 3-6mm for minor levelling, up to 15-20mm for uneven floors
Default 1.6 kg/m2/mm - check your product data sheet
Most self-levelling compounds are sold in 20kg or 25kg bags
Covers cuts, breakages and uneven ground. 10% is a typical starting point.
Self-levelling compound estimate
Enter floor area and pour depth to see your estimate
How to calculate self-levelling compound
The formula is simple: total kg = area (m2) x depth (mm) x coverage rate (kg per m2 per mm).
The coverage rate is the critical variable. Most standard self-levelling compounds quote approximately 1.6 kg per m2 per mm depth, but this varies between products - some are as low as 1.4 and others as high as 1.8. Always check the data sheet for your specific product before ordering.
Add 10% wastage to account for slight variations in floor flatness, the compound flowing into cracks and the need to round up to whole bags. Round your total up to the nearest bag - you cannot meaningfully use a partial bag.
Pour depth guide
| Application | Typical depth | Product type |
|---|---|---|
| Minor levelling (new concrete, minor dips) | 2-5mm | Standard SLC |
| Moderate unevenness | 5-10mm | Standard SLC |
| Significant undulations | 10-20mm | Standard or deep-fill SLC |
| Major re-levelling | 20-50mm | Deep-fill SLC (multi-pour) |
Getting the best results from floor leveller
Self-levelling compound rewards preparation. The most common mistakes are skipping primer, applying it over a dusty or contaminated surface, mixing it too thick, or not having enough product ready before you start pouring.
Mix to a smooth, creamy consistency - if you can see lumps, mix longer. Once mixed, it typically has a working time of 15-30 minutes. Do the whole area without stopping; joining fresh compound to a batch that has started to set produces a visible ridge.
Temperature matters. Do not apply below 5C or when frost is forecast. In warm weather, the compound sets faster - this is not a problem as long as you work quickly, but check the minimum pour temperature on your product.
Related calculators
Work out floor screed quantities in bags, kg and tonnes for sand:cement and anhydrite screed.
Work out how much concrete you need for a shed base, garage base or garden room.
Calculate cement bags and sand for brickwork and blockwork. Adjustable mix ratios.
Work out how many bags of render you need for any wall area, with openings deducted.
Frequently asked questions
Planning estimates only
These results are estimates for planning purposes only. Actual material quantities can vary based on site conditions, compaction, wastage, product size, installation method and supplier guidance. For structural, safety-critical or regulated work, always consult a qualified professional.