Free calculator
How much paint does this room actually need?
Walls, ceiling and trim, with the waste that paint labels leave out.
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How the paint estimate works
The calculator measures the four walls, subtracts standard allowances for doors and windows, multiplies by the number of coats, and divides by the coverage printed on the tin.
Why the tin is only a starting point
Coverage depends on the surface, colour change and roller. A dark colour over a light wall can need three coats. Buying one extra can is cheaper than a second trip with a colour that no longer matches.
Who it is for
Anyone painting a room who wants a shopping number before standing in the paint aisle.
Frequently asked questions
What coverage should I enter?
The figure on the tin for a single coat, usually 10–12 m² per litre for emulsion. If the wall is porous or the colour change is large, use the lower end.
Does it include the ceiling?
No. Wall area only. Measure the ceiling separately and divide by the same coverage.
How much extra should I buy?
One 1 L or one 5 L can beyond the calculated amount is usually enough for touch-ups, depending on the room size.