Example Data Table
| Room | Area | Depth | Rate | Waste | Bag Size | Estimated Bags |
|---|---|---|---|---|---|---|
| Kitchen | 120 ft² | 6 mm | 1.70 kg/m²/mm | 10% | 20 kg | 7 bags |
| Hallway | 18 m² | 4 mm | 1.70 kg/m²/mm | 8% | 20 kg | 7 bags |
| Basement | 320 ft² | 10 mm | 1.80 kg/m²/mm | 12% | 50 lb | 27 bags |
Formula Used
Area from dimensions: area = length × width
Total depth: total depth = average depth × number of pours
Wet volume: litres = area in m² × total depth in mm
Base compound mass: kg = area in m² × depth in mm × coverage rate
Mass with waste: total kg = base kg × (1 + waste % ÷ 100)
Bags needed: rounded bags = ceiling(total kg ÷ bag kg)
Primer: litres = area in m² × primer coats ÷ primer coverage
Total cost: compound cost + primer cost + other cost + tax
How To Use This Calculator
- Enter a known area, or choose length and width.
- Add the average pour depth from floor level checks.
- Enter the coverage rate from the selected Mapei data sheet.
- Add bag size, waste allowance, primer details, and prices.
- Press calculate to see the result above the form.
- Download the CSV or PDF for purchase records.
Planning A Self Levelling Pour
A self levelling pour looks simple, but quantity errors are costly. Too little compound can leave dry edges. Too much compound ties money in unused bags. This calculator turns room size, depth, waste, primer, and price into a clear material plan. It works best when you measure the floor after cleaning it.
Why Coverage Rate Matters
Self levelling compounds are sold by weight. Coverage changes with product density, water ratio, and the planned thickness. Mapei products also have different yield values. Always check the current technical data sheet. Then enter that value as kilograms per square metre per millimetre. The default value is only a planning estimate. It should not replace site instructions.
Measuring The Floor
Start with the total floor area. You can enter a known area, or use length and width. Next, find the average pour depth. Measure low spots across the room. Add them together, then divide by the number of checks. Do not use the deepest hole as the only depth. That may overstate the order.
Waste And Practical Allowance
Waste is normal during mixing, spreading, priming, and edge work. A small, square room may need less allowance. A broken slab, many doorways, or several mixes may need more. The waste field helps cover these issues. It also gives a safer bag count after rounding.
Primer And Cost Checks
Primer is important because it helps control absorption. The calculator estimates primer by area, coats, and coverage. It also rounds bottles upward. You can add bag price, primer price, labour, and tax. This gives a basic budget before purchase.
Using The Result
Read the exact bag count first. Then use the rounded bag count for ordering. Review total mass if the floor has load limits. Check the calculated volume against site mixing capacity. Keep the example table nearby when training staff. Before pouring, confirm temperature, substrate condition, edge sealing, and product depth limits. Final orders should follow the selected Mapei bag label and data sheet.
Record Keeping
Save each result with the job name and room name. The CSV file helps compare rooms. The PDF is useful for approval, purchasing, and site notes before work starts. It also supports later waste checks.
FAQs
1. What coverage rate should I use?
Use the rate from the selected Mapei technical data sheet. Products vary by density and depth range. The default value is only a planning estimate.
2. Why does the calculator round bags upward?
Compound is bought in full bags. Rounding upward reduces the risk of stopping during a pour because material runs short.
3. Should I include waste allowance?
Yes. Waste covers mixing loss, surface variation, spreading loss, and small measurement errors. Difficult floors usually need a larger allowance.
4. Can I use feet and inches?
Yes. You can enter area in square feet and depth in inches. The calculator converts values before applying the formula.
5. Does this replace the product data sheet?
No. Always follow the current product data sheet, bag label, surface preparation rules, water ratio, and depth limits.
6. How is primer estimated?
Primer is estimated from area, number of coats, and coverage per litre. Bottles are rounded upward for ordering.
7. Why is average depth important?
Average depth gives a more realistic material estimate. Using only the deepest low spot can overstate the required compound.
8. Can I calculate several rooms?
Calculate each room separately, then add the rounded bag counts. This keeps waste and depth differences easier to review.