Paint Calculator
Based on 12 m² per litre per coat. Deducts about 1.8 m² per door or window.
How much paint do I need?
Enter the room's length, width and height, the number of coats and how many doors and windows to deduct, and the calculator works out the wall area and the litres of paint, based on a typical emulsion coverage of 12 square metres per litre per coat. Two coats is standard for a solid, even finish, and more if you are going from a dark colour to a light one.
Coverage varies by paint and surface: bare plaster and fresh filler drink the first coat, so a mist coat of watered-down emulsion first saves paint overall. This figure is for walls, so add separately for the ceiling, and use gloss or eggshell coverage figures for woodwork.
Frequently asked questions
Is the paint calculator free?
Yes. It is completely free, with no sign-up and nothing to install. It runs entirely in your browser.
How accurate is it?
It gives a reliable estimate for ordering based on standard UK figures, but real quantities vary with ground conditions, wastage and how materials settle. Always add a margin and confirm with your supplier before buying.