Paint Calculator
Estimate paint for four walls, allowing for openings, coats and waste. Enter the coverage specified for your chosen product.
Your result
- Paint to allow for
- 9.02 L
- Wall area excluding openings
- 41 m²
- Estimated paint cost
- $108.24
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Formula
Net wall area = 2 × (length + width) × height − openings; paint = net area × coats ÷ coverage × (1 + waste ÷ 100).
Worked example
The initial example uses the following assumptions. Its result is computed by the same engine as the calculator. Measurements are metric and money amounts use USD; these are illustrative inputs, not market prices.
- Room length
- 5 m
- Room width
- 4 m
- Wall height
- 2.5 m
- Total door and window area
- 4 m²
- Number of coats
- 2
- Coverage per unit of paint
- 10 m²/L
- Waste allowance (%)
- 10
- Paint price
- 12 per L
- Paint to allow for: 9.02 L
- Wall area excluding openings: 41 m²
- Estimated paint cost: $108.24
Assumptions and limitations
Ceilings are not included. Product coverage is an assumption, not a guarantee: texture, porosity and application affect the amount needed. Round the estimate to available can sizes.
Questions about this calculation
Does this include the ceiling?
No. This tool covers the four walls only. Calculate ceiling area separately.
Which gallon does imperial coverage use?
Choose US or UK units explicitly. Their gallons have different volumes, and coverage and price labels change together.
Useful next steps
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