How Much Paint Do I Need for Walls?
Quick Answer
A typical 4m × 3m room needs ~5 litres for 2 coats
Based on: 4 walls at 2.4m ceiling height = ~29m² (after deducting door and window), matt emulsion at 12m²/L
How We Calculated This
Wall paint quantity is based on the total paintable area and the paint’s coverage rate:
- Wall area: 2 × (4 + 3) × 2.4 = 33.6m²
- Deduct door (~1.8m²) and window (~1.5m²) = ~30.3m²
- Paint needed per coat: 30.3 ÷ 12 = ~2.5L
- Two coats: 2.5 × 2 = ~5L
Coverage Rates by Paint Type
- Matt emulsion: 12–14m²/L (most common for walls)
- Silk emulsion: 13–15m²/L
- Eggshell: 12–14m²/L
- Trade-quality matt: 14–17m²/L (better coverage, fewer coats)
- Kitchen & bathroom paint: 12–13m²/L
Tin Sizes Available in the UK
- Tester pot: 75ml (covers ~0.75m²)
- Small tin: 1.25L (covers ~15m² per coat)
- Medium tin: 2.5L (covers ~30m² per coat)
- Large tin: 5L (covers ~60m² per coat)
- Trade tin: 10L (covers ~120m² per coat)
Factors That Increase Paint Usage
- Porous surfaces: New plaster, bare plasterboard — use a mist coat first
- Dark to light colour change: May need 3+ coats
- Textured walls: Woodchip or Artex increases area by 15–30%
- Roller vs brush: Rollers use slightly more paint but are faster
Tips
Always buy all your paint at once to ensure batch consistency. For new plaster, apply a mist coat (emulsion diluted with water) before your first full coat. Stir paint thoroughly before use, and keep a wet edge to avoid lap marks.