Paint calculator – litres per m² and gallons per sq ft
How much paint for walls and ceilings: coverage per litre and per gallon, how to measure a room, number of coats and a worked example.
Paint (litres) = area (m²) × number of coats ÷ coverage (m² per litre)
| Paint | Coverage per coat |
|---|---|
| Interior emulsion / latex | 8–12 m² per litre ≈ 350–400 sq ft per US gallon |
| Primer / sealer | 8–10 m² per litre |
| Exterior masonry paint | 5–8 m² per litre (rough surfaces less) |
Example room 4 × 5 m, 2.6 m high
Walls 2 × (4 + 5) × 2.6 = 46.8 m², minus door and window ≈ 4 m² → 43 m²; ceiling 20 m². Two coats: (43 + 20) × 2 ÷ 10 ≈ 12–13 litres (about 3.3 US gallons), plus primer on new plaster or plasterboard.
Tips
- New plaster and plasterboard need a mist coat or primer first.
- Strong colour changes may need a third coat.
- Buy all paint from the same batch for one wall.
AI Onin is an AI assistant for construction: material quantities, cost estimates in your currency, bill of quantities checks and site photo analysis. Values are typical and approximate – follow the manufacturer's data sheet, your local code and your engineer.