Estimate paint needed for walls based on room dimensions and coats.
Estimate paint needed for walls based on room dimensions and coats.
Enter values above and click Calculate — results will appear here with the formula explained.
Paint estimation chains four assumptions: perimeter times height gives gross wall area; standard doors and windows subtract fixed allowances; coats multiply demand; and the tin's stated coverage converts area into liters. Each link carries slop, hence the built-in 10% buffer.
Coverage ratings assume smooth primed surfaces. Fresh drywall, textured plaster and dramatic color changes can consume 30–50% beyond the label figure — dark-over-light transitions especially reward tinted primer before counting finish coats.
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Paint estimation chains four assumptions: perimeter times height gives gross wall area; standard doors and windows subtract fixed allowances; coats multiply demand; and the tin's stated coverage converts area into liters. Each link carries slop, hence the built-in 10% buffer. Formula: walls = 2×(L+W)×H − openings; paint = area × coats ÷ coverage × 1.1
Paint Calculator: Estimate paint needed for walls based on room dimensions and coats. Formula: walls = 2×(L+W)×H − openings. Example: A 5×4 m room, 2.
Estimate paint needed for walls based on room dimensions and coats. Formula: walls = 2×(L+W)×H − openings; paint = area × coats ÷ coverage × 1.1
| Field | What to enter |
|---|---|
| Room length (m) | e.g. 5 |
| Room width (m) | e.g. 4 |
| Wall height (m) | e.g. 2.5 |
| Doors | Enter a value |
| Windows | Enter a value |
| Coats | Enter a value |
| Paint coverage (m²/L) | Enter a value |
All fields use the exact formulas shown below — results include step-by-step breakdowns you can verify by hand.
Paint estimation chains four assumptions: perimeter times height gives gross wall area; standard doors and windows subtract fixed allowances; coats multiply demand; and the tin's stated coverage converts area into liters. Each link carries slop, hence the built-in 10% buffer.
Coverage ratings assume smooth primed surfaces. Fresh drywall, textured plaster and dramatic color changes can consume 30–50% beyond the label figure — dark-over-light transitions especially reward tinted primer before counting finish coats.
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A 5×4 m room, 2.5 m ceilings: 45 m² gross, minus one door and two windows ≈ 41.7 m². Two coats at 10 m²/L needs 9.2 L — grab three 4-L tins.
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