Basic Formula
Paint required per coat = paintable area ÷ stated coverage per litre. Multiply by the number of coats, then allow an appropriate margin for the job.
Area Calculations
| Surface | Calculation |
|---|---|
| Rectangular wall | width × height |
| Room walls | add each wall area |
| Ceiling | length × width |
| Door/window deduction | opening width × opening height |
| Multiple coats | one-coat litres × number of coats |
Worked Example
Example only: 48 m² of paintable area ÷ a product coverage of 12 m²/L = 4 L per coat. Two coats = 8 L before any allowance. Always use the coverage on the actual product.
What Changes Coverage
- Porous or rough surfaces.
- Colour change and opacity.
- Application method.
- Primer or undercoat requirements.
- Surface condition and product type.