Construction
Paint calculator
Enter room dimensions, number of coats, and paint coverage. The calculator subtracts standard door (2 m²) and window (1.5 m²) areas to give you the liters of paint to buy.
Gross wall area
48.6 m²
Net paintable
43.6 m²
Paint needed
8.72 L
Formula
Most interior paints cover 10-12 m² per liter on a smooth, primed surface. Rough surfaces (textured plaster, masonry) drop coverage by 30-50%. The first coat on bare drywall absorbs more — add 20% if you're skipping primer.
Doors and windows are subtracted using rough averages (2 m² per door, 1.5 m² per window). For unusual shapes, measure exactly and adjust the subtraction yourself.
Always buy 5-10% extra to handle touch-ups later and avoid color-match issues between batches. Store the leftover for repairs.
Examples
- 015×4 m room, 2.7 m ceilings, 2 coats, 1 door, 2 windows, 10 m²/L coverage→ Walls 48.6 m², net 43.6 m², ×2 coats = 87.2 m², ÷ 10 = 8.72 L
- 023×3 m bedroom, 2.5 m ceilings, 2 coats, 1 door, 1 window→ Walls 30 m², net 26.5 m², ×2 = 53 m², ÷ 10 = 5.3 L
FAQ
- This calculator does walls only. For ceiling, compute length × width separately and add to the wall area. Ceilings often use a different paint (matte white) anyway.