Paint Calculator
Enter the room size, the area of doors and windows, the number of coats and the paint coverage to estimate the paint you need.
This result is an estimate only. Check with your bank or the relevant authority before making decisions.
How it is calculated
- Wall area = 2 × (length + width) × height − door and window area
- Litres of paint = area × number of coats ÷ coverage
- 5-litre cans = litres ÷ 5, rounded up
This estimate covers walls only and does not include the ceiling.
Worked example
A 4 m × 3 m room, 2.7 m high, 3.5 m² of doors and windows, 2 coats, coverage 10 m² per litre:
- Wall area = 2 × (4 + 3) × 2.7 − 3.5 = 34.30 m²
- Paint = 34.30 × 2 ÷ 10 = 6.86 litres
- 5-litre cans = 2 cans
Why your number may differ
Coverage depends on the paint you choose and is printed on the tin. Rough or porous walls soak up more paint. This is only an estimate.
Frequently asked questions
How is wall paint calculated?
Take the wall area, subtract the doors and windows, multiply by the number of coats, then divide by the paint coverage per litre.
Where do I find the paint coverage?
It is printed on the paint tin. Rough or porous walls need more paint.
Is the ceiling included?
No. This calculator estimates the walls only.