Paint Calculator
About the Paint Calculator
Work out how many litres of paint a room needs. Enter the wall area, the number of coats and the coverage printed on the tin, and the calculator shows the amount to buy, so you avoid both running short and carrying home spare tins.
This tool works in your browser: the files and text you use are processed on your device and are not uploaded.
How to use it
- Enter the wall length and height, and how many walls.
- Set the number of coats and the coverage rate (ft² per litre).
- Read the litres and gallons required.
Frequently asked questions
How much wall does a litre of paint cover?
Around 100–120 ft² per litre (about 10 m²/L) for a single coat of typical emulsion on a smooth, primed wall. Rough, textured, or unprimed surfaces absorb more and cover less.
How many coats do I need?
Two coats is standard for an even finish, especially over a different colour. A fresh, porous, or patchy surface may need a primer plus two topcoats.
Should I subtract doors and windows?
For a quick estimate you can paint the gross wall area — the small over-estimate is a useful buffer. For large glazed areas, subtract them and add ~10% back for touch-ups and waste.