How many litres of paint do you need?
Litres and cans from wall area, coverage per m² and number of coats.
How to use the calculator
Calculate the wall area: multiply the room perimeter by the ceiling height. Windows and doors can be subtracted from the result — unlike wallpaper, paint does not need whole strips, and an opening honestly saves material. Check the coverage per litre on the can: for different paints it is 8–12 m²/l, and lower for textured paints and primers.
Two coats is the usual. One coat is enough when refreshing the same shade or painting over a primer in a close colour. The first coat on fresh plaster soaks in more — allow 20–30% above the rate stated on the can.
Where the consumption comes from
The manufacturer states consumption for a perfectly flat, prepared surface. In practice losses add up: some paint stays on the roller, in the tray and on the brushes, some goes into touching up scratches after drying. That is why the calculator rounds the volume up rather than down, and suggests buying a can with a 5–10% margin.
How many cans to buy
If the required volume is 9 litres and the cans are 2.5 l, you get four cans and 10 litres of paint. An extra litre is better than a trip to the shop for the missing amount: tinted paint is often made to order, and the shade in a new batch may differ. And mix the cans in one container before painting — that way the colour will be the same on all walls.
Frequently asked questions
What coverage should I use?
Check the can: usually 8–12 m² per litre for walls in one coat. On fresh plaster the first coat takes 20–30% more, because the surface absorbs it.
How many coats should I count?
Two coats is the standard when changing colour. One coat is enough when you are refreshing the same shade or painting over a primer of a similar colour.
Do I need a spare?
Yes, 5–10%: some paint stays on the roller, the brushes and in the tray, and you want a little left for touching up scratches once it dries.
What if the paint only comes in 2.5 and 9 litre cans?
The calculator works out the volume you need; cans are then counted by the size you choose, rounded up. Combine can sizes by hand if you want the cheapest mix — the litre figure is what matters.
Related tools
Checked: 26 October 2026. For reference only — the result depends on the material and the skill of the installer.