Paint Calculator
Calculate paint and primer quantities for walls, ceiling and trim.
About Paint Calculator
Paint scales linearly with both area and coat count, so the second coat costs exactly as much as the first. Coverage varies with surface porosity, and bare plaster can absorb far more than the quoted figure. Buying in five litre tins rather than litres is substantially cheaper per litre, so rounding up to whole tins is usually the right call.
Formula
Paint
Litres = net area × coats ÷ coverage per litre
- coverage
- Area one litre covers in a single coat, typically 10 to 12 m²
- primer
- Applied as a single coat, so it needs half what two topcoats do
Worked example
With the default values below, Paint Calculator returns Paint Required of 8.55. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Wall areaminimum 0 m2
- 55 m2
- Openings to deductminimum 0 m2
- 8 m2
- Number of coatsaccepts 1–6
- 2
- Coverage per litreminimum 0.1 m2
- 11 m2
- Primer requiredone of Yes, No
- Yes
Results
- Paint Required
- 8.55 L
- Net Area to Paint
- 47.00 m2
- Primer Required
- 4.27 L
- Total Paint and Primer
- 12.82 L
- Five Litre Tins to Buy
- 3
Step by step
- 1Values used
- 2Paint
- 3Paint Required= 8.55 L
- 4Net Area to Paint= 47.00 m2
- 5Primer Required= 4.27 L
- 6Total Paint and Primer= 12.82 L
- 7Five Litre Tins to Buy= 3
Assumptions and limits
- The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, fees or charges or compounding frequency into account.
- Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.
How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.
Frequently Asked Questions
How is Paint calculated?
Litres = net area × coats ÷ coverage per litre Paint scales linearly with both area and coat count, so the second coat costs exactly as much as the first. Coverage varies with surface porosity, and bare plaster can absorb far more than the quoted figure.
Why does Paint matter?
Buying in five litre tins rather than litres is substantially cheaper per litre, so rounding up to whole tins is usually the right call.
What values do I need to enter?
This calculator takes 5 inputs: Wall area, Openings to deduct, Number of coats, Coverage per litre, Primer required. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.