Paint calculator for a room
Room dimensions, number of coats and the area of doors and windows. We give you litres, tins and cost.
Your figures
Result
- Paredes4590,0 %
- Huecos descontados510,0 %
- Tins to buy (ud.)
- 2
- Cost
- $64.00
- Area to paint (m²)
- 40.0
- Of which walls (m²)
- 45.0
- Of which ceiling (m²)
- 0.0
- Total area across all coats (m²)
- 80.0
What we assume
- The room is treated as a rectangular box. Alcoves and sloping ceilings need adjusting by hand.
- The default coverage is about 10 m² per litre per coat, which is typical for plastic paint on a smooth prepared wall.
- A porous or previously unpainted wall drinks far more on the first coat. Bare plaster can halve the coverage.
- A strong colour change often needs three coats, not two.
How it is calculated
The wall area is the perimeter times the height, minus the doors and windows. The ceiling, if you are painting it, is length times width. Multiply by the number of coats and divide by the coverage:
paint = (walls + ceiling - openings) x coats / coverage
Where the estimate goes wrong
Almost always the coverage figure. The number on the tin is measured on a smooth, sealed, prepared surface. On bare plaster, on a textured wall, or over a much darker colour, you can use half again as much on the first coat. If in doubt, buy the extra tin: touching up later from a different batch shows.
An example
A room of 5 by 4 by 2.5 with the ceiling included, 5 m² of openings and two coats needs about 12 litres. That is roughly 60 m² of wall plus 20 of ceiling, painted twice.
Frequently asked questions
Do I need to subtract doors and windows?
Yes, if they add up to a meaningful area. A single door is about 2 m² and a window 1.5 to 2 m². In a small room that is easily 10% of the total.
Two coats or three?
Two over a similar colour on a prepared wall. Three if you are going light over dark, painting bare plaster, or using a strong colour, where coverage is usually poorer.
Should I buy extra?
Round up to the next tin and keep the remainder. Touching up months later with paint from another batch is visible, even in the same colour.
Keep calculating
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