Paint, Putty & Plasterboard
Quick answer: For 40 m² of walls you need about 60 kg of skim coat (3 × 25 kg bags) and 10 L of paint for two coats (one 15 L bucket).
Calculate putty, paint and plasterboard system (boards, profiles, screws, Q1-Q3)
How the calculation works
Enter the room dimensions, openings (doors, windows) and whether to include the ceiling. The calculator works out the net wall and ceiling area and from it the amount of putty, paint and, if needed, plasterboard and accessories.
Formula and assumptions
Wall area = perimeter × height − openings; ceiling = length × width. Putty ≈ 1.5 kg/m² (2 coats), 25 kg bags. Paint ≈ 0.125 L/m² per coat × 2 coats = 0.25 L/m², 15 L buckets. Everything is rounded up. Consumption is indicative and depends on the substrate and product.
Worked example
Net area 40 m²: putty 1.5 × 40 = 60 kg → 3 bags × 25 kg = 75 kg. Paint 0.125 × 2 × 40 = 10 L → 1 bucket of 15 L.
More worked examples
- Walls and ceiling of 85 m² net: putty 1.5 × 85 = 127.5 kg → 5.1 → 6 bags of 25 kg (150 kg). Paint 0.125 × 2 × 85 = 21.25 L → 2 buckets of 15 L (30 L).
- Room 4 × 5 m, height 2.6 m, one door of 2 m² and two windows of 3 m² in total, with ceiling: walls 18 × 2.6 = 46.8 − 5 = 41.8 m², ceiling 20 m², net 61.8 m². Putty 92.7 kg → 4 bags; paint 15.45 L → 2 buckets.
Putty and paint by net area
| Area (m²) | Putty (kg) | Bags of 25 kg | Paint (L) | Buckets of 15 L |
|---|---|---|---|---|
| 20 | 30 | 2 | 5 | 1 |
| 40 | 60 | 3 | 10 | 1 |
| 60 | 90 | 4 | 15 | 1 |
| 100 | 150 | 6 | 25 | 2 |
| 150 | 225 | 9 | 37.5 | 3 |
What affects real consumption
- Absorbent or uneven walls increase putty and paint use.
- Dark colours and low-opacity paints need an extra coat.
- Application method: roller, brush or spray.
Common mistakes
- Forgetting the ceiling or not subtracting doors and windows from the wall area.
- Assuming a single coat; the calculator counts two layers of putty and two of paint.
- Ignoring dark colours and very absorbent walls, which need an extra coat or primer.
- Buying exactly the calculated amount instead of whole bags and buckets with a small reserve.
Frequently asked questions
Does the calculator subtract doors and windows?
Yes – enter openings separately and they are subtracted from the wall area.
Why is paint consumption only indicative?
Coverage depends on the product, colour and substrate; use the paint's data sheet for exact figures.
How much putty and paint do I need for 100 m²?
About 150 kg of putty (6 bags of 25 kg) and 25 L of paint (2 buckets of 15 L), counting two layers of each.
How many coats does the calculator assume?
Two layers of putty and two coats of paint. If your product or colour needs more, multiply the paint amount accordingly.
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Publisher: Art-Visum d.o.o. · Content reviewed:
Calculations use common consumption rates and manufacturers' technical data sheets; results are estimates. Methodology · Standards · About · Worked example