Paint Calculator
Litres of paint needed for a room, by dimensions and coats.
Your result appears here
Fill in the fields on the left and press Calculate. The answer, the breakdown and a copy button all land in this card.
How it is calculated
Wall area = perimeter × height − doors/windows; Paint needed = wall area × coats ÷ coverage
Perimeter is 2 × (length + width), assuming all four walls are painted.
Worked example
A 4 × 3.5 m room with 2.7 m walls has 40.5 m² of wall. Minus 3 m² for doors and windows, two coats at 10 m²/litre coverage needs 7.5 litres.
Questions people ask
This estimates walls only. For a ceiling, add its area (length × width) at the same coverage rate.
Paint is sold in fixed tin sizes and touch-ups are common, so round up to the next full tin rather than buying the exact litres.