Example 1 — Small room without deductions
- Length: 4 m
- Width: 3 m
- Height: 2.6 m
Wall area: 36.4 m²
This is a simple starting point for painting or estimating finishing materials in a small room.
Wall area
Calculate the total wall area in a room, with the option to subtract doors, windows, and other openings.
This calculator quickly estimates wall area for painting, skim coat, wallpaper, or other finishing work. The result can be reduced by openings to better reflect the real material requirement. Calculate paint with the paint requirement calculator, plaster with the plaster requirement calculator, and bricks with the brick requirement calculator.
Results
Enter data and click Calculate.
How the results are calculated
Walls = 2×(length+width)×height, optionally + length×width for the ceiling, minus windows, doors and extra openings. Door height is fixed at 2.0 m; window/door width and height use cm (US: in).
How to use this calculator
- Enter the room length, width, and height.
- If the calculator includes opening fields, add the area of doors, windows, or other elements you do not want to include.
- Check the net result, which is the actual wall area after deductions.
- Use that result as the base for further calculations such as paint, plaster, or wall covering.
Example scenarios
Example 2 — Room with a window and door deducted
- Length: 5 m
- Width: 4 m
- Height: 2.7 m
- Openings: 4.5 m²
Net wall area: 44.1 m²
Subtracting openings gives a more realistic purchasing estimate, especially for paint, skim coat, and wallpaper.
Example 3 — Larger room for finishing work
- Length: 6 m
- Width: 4.5 m
- Height: 2.8 m
- Openings: 5.2 m²
Net wall area: 53.6 m²
In larger rooms, even a small input error can easily change the result by several square metres.
FAQ
How is wall area calculated?
Most often as the room perimeter multiplied by the height. After that, you can subtract windows, doors, and other openings.
Should doors and windows be subtracted?
If you want a more accurate material estimate, usually yes. If you only need a quick approximation, some people leave a small margin and do not deduct every small opening separately.
Is the ceiling included in this result?
No, not if the calculator is designed to calculate wall area only. The ceiling should be calculated separately or with another calculator if available.
Why calculate wall area separately?
Because it is the base for many follow-up calculations: paint, skim coat, wallpaper, decorative brick, wall panels, or internal insulation.
Is the net result better than the gross result?
For purchasing, usually yes, because it reflects the real area that needs to be covered. The gross result can still be useful for general planning.
Does this calculator also work for a corridor or an irregular room?
It works very well for simple rectangular spaces. For more complex layouts, the best approach is to split the room into simpler sections and add the results together.
What most often reduces accuracy?
Unit mistakes, ignored slopes, incorrect deductions, or entering room height too roughly. If the result is used for buying material, accurate measurement matters.
What should I calculate after wall area?
Most often paint, plaster, or another wall-finishing material. If you are planning a full renovation, floor area and room volume are also useful next steps.