Decorating & Walls calculator
Wall Paint Calculator
Turn measured wall area into a wall-paint quantity using coat count, product coverage and an optional extra allowance.
Turn measured wall area into a wall-paint quantity using coat count, product coverage and an optional extra allowance. Keep the dimensions and units consistent, then check the figures that describe the product or layout you will really use. In this calculation, coverage rate, coats and absorbency can change the answer materially. Fresh plaster, repaired areas and major colour changes can absorb or hide differently from an already painted wall, so the stated coverage rate may not match the first coat.
What you need to enter
The Wall Paint Calculator uses the following project information to calculate the result.
- Area
- Number of coats
- Coverage per unit
- Extra allowance (%)
Calculator result
Required coating quantity, rounded buying quantity
How the Wall Paint Calculator works
For paint for one or more measured wall surfaces, the calculator uses quantity = area × coats ÷ coverage × (1 + wastePct/100). The mathematics is only one part of the estimate: getting coverage rate, coats and absorbency right usually matters more to the real-world result than extra decimal places. Unit conversion happens before the calculation.
Wall Paint Calculator worked example
Wall Paint Calculator example: A 4.8 m × 2.4 m wall covers 11.52 m². Two coats of paint rated at 12 m²/L need 1.92 L before allowance; adding 10% gives about 2.11 L. Subtract only openings that genuinely will not be painted. Use the numerical result as the starting point, then verify coverage rate, coats and absorbency against the material, layout or equipment actually being used.
Important calculation assumptions
For paint for one or more measured wall surfaces, fresh plaster, repaired areas and major colour changes can absorb or hide differently from an already painted wall, so the stated coverage rate may not match the first coat.
Frequently asked questions
Which real-world inputs does the Wall Paint Calculator rely on?
To estimate paint for one or more measured wall surfaces, measure the surface area that will actually be coated, then enter the number of coats and the coverage figure printed for the exact product. Use measured or manufacturer-specific values wherever they are available.
How can errors in coverage rate, coats and absorbency change the Wall Paint Calculator result?
Do not chase extra decimal precision in the Wall Paint Calculator until you have realistic values for coverage rate, coats and absorbency. Fresh plaster, repaired areas and major colour changes can absorb or hide differently from an already painted wall, so the stated coverage rate may not match the first coat.
Should I order exactly the amount shown by the Wall Paint Calculator?
For the Wall Paint Calculator, the numerical answer still needs a real-world check. Round wall-paint quantity up to sensible tin sizes. Major colour changes or fresh plaster may justify an extra coat beyond the theoretical coverage calculation.