Paint calculator for a room
Enter the room size, the area of doors and windows and the number of coats to see how many litres to buy.
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How to use it
- Enter room length, room width, wall height, doors and windows area, paint the ceiling too and number of coats.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
Wall area = 2 × (length + width) × height − openings, plus the ceiling (length × width) if chosen. Litres = area × coats ÷ coverage. Cans = litres ÷ can size, rounded up.
Example
Inputs: Room length = 5 m, Room width = 4 m, Wall height = 3 m, Doors and windows area = 4 m², Paint the ceiling too = no. Result: Paint needed: 10 L; Cans: 3; Surface to paint: 50 m².
Limits and caveats
- The coverage on the can assumes a smooth surface; rough or new walls take more.
- Primer and filler are not included, so work them out with their own coverage.
Questions about this tool
How much paint for a 4 × 5 m room?
With 3 m walls, 4 m² of openings, two coats and 10 m²/L coverage you need 10 litres for the walls, 14 with the ceiling.
How far does a litre of paint go?
Usually 8 to 12 m² per coat on a smooth surface; the exact figure is on the can.
How many coats do I need?
Two as a rule, three when covering a dark colour with a light one or on new walls after primer.