Paint Calculator
Estimate the litres of paint a room needs from its size, coats and coverage, minus openings.
How to use it
- Enter the room size Length, width and wall height in metres.
- Set coats and coverage Coverage is on the paint tin, often 10–12 m²/L.
- Subtract openings Add the area of doors and windows to skip.
Examples
| 5×4×2.5, 2 coats | ~9 L |
|---|---|
| coverage 10 | per coat |
About this tool
Buying paint is a guessing game without the numbers. This calculator takes your room dimensions, the number of coats and the paint’s coverage, then subtracts the area of doors and windows to estimate how many litres you’ll actually need.
It assumes you’re painting the four walls; add openings to avoid over-buying. The result is a solid starting point — pick up a little extra for touch-ups. All the maths runs in your browser.
Frequently asked questions
What coverage should I use?
Most emulsion paints cover 10–13 m² per litre per coat. Check the tin — rough or porous surfaces use more.
Why subtract doors and windows?
You don't paint over them, so removing their area gives a more accurate, less wasteful estimate.
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Updated June 14, 2026