Wall Area
Free Wall Area calculator with clear step-by-step results.
About Wall Area
Wall area is perimeter times height, less the openings - and deducting openings matters far more here than it does for a ceiling, since doors and windows can easily be 15% of a small room's wall surface. Paint is then sized for two coats at the coverage rate on the tin.
Formulas
Net wall area
Net = perimeter x height - (doors x door area + windows x window area)
Paint required
Litres = net area x 2 coats / coverage per litre
Worked example
With the default values below, Wall Area returns Net wall area to finish of 35.40. Change any input above and every figure here is recalculated in your browser.
Inputs used
- Room perimeterminimum 0.1 m
- 18 m
- Wall heightminimum 0.1 m
- 2.4 m
- Doorsaccepts 0–30
- 2
- Windowsaccepts 0–30
- 3
- Area per doorminimum 0.1 m2
- 1.8 m2
- Area per windowminimum 0.1 m2
- 1.4 m2
- Paint coverageminimum 1 m2/L
- 12 m2/L
Results
- Net wall area to finish
- 35.40 m2
- Gross wall area
- 43.20 m2
- Area of doors and windows deducted
- 7.80 m2
- Paint for two coats
- 5.90 L
Step by step
- 1Values used
- 2Net wall area
- 3Paint required
- 4Net wall area to finish= 35.40 m2
- 5Gross wall area= 43.20 m2
- 6Area of doors and windows deducted= 7.80 m2
- 7Paint for two coats= 5.90 L
Assumptions and limits
- The result is derived only from the 7 inputs listed above. Anything not among them is not part of the calculation.
- In particular, this calculator does not take inflation, tax, 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
Should I deduct small openings?
Deduct anything above about half a square metre. Smaller openings are more than offset by the cutting-in around them.
Is coverage on the tin realistic?
Optimistic. Quoted coverage assumes a smooth, sealed, previously painted surface. On new plaster or a colour change, plan for 15-20% less.