Walls
Calculated as 2 × (length + width) × height.
Construction
Paint calculator
Calculate wall or ceiling area and estimate the paint needed from coats, coverage and margin.
Paint area calculator
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m²
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Doors and windows
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Publicidad
How to measure a room
For a rectangular room, measure length, width and wall height. The calculator uses perimeter for walls and length by width for ceiling.
Ceiling
Calculated as length × width, without subtracting doors or windows.
Openings
Add doors and windows to subtract them from the wall area.
Nonrectangular surfaces
For a wall measured in sections or an irregular shape, calculate the area first and enter the total in Manual area mode.
Frequently asked questions
How do you calculate the square meters of a wall?
Multiply width by height. For several walls, add each area or multiply the perimeter of a rectangular room by its height.
How do you calculate paint for a room?
Calculate net area, multiply by the number of coats and divide by the paint coverage, then add a margin.
Should you subtract doors and windows?
Yes for walls. The calculator subtracts doors and windows from walls, not the ceiling.
How much paint do you need per square meter?
It depends on manufacturer coverage. A common starting value is 10 m²/L, but check the product label.
Why must you enter paint coverage?
It varies by paint type, surface, previous colour and application method. Using the coverage stated on the label improves the estimate.
How do you account for two coats?
Multiply the net surface area by 2 before dividing by the coverage rate. The calculator does this automatically from the number-of-coats field.
How much extra paint should you buy?
The waste allowance is editable. It can help when a wall is porous, stained or previously painted a very dark colour, but it is not a universal rule.
How do you calculate doors and windows measured in centimeters?
You can enter opening width and height in centimetres. The calculator converts them to metres before adding the area.
How do you choose container size?
Use an actual container size available for the paint you plan to buy. The calculator rounds up and shows the estimated remainder.