Wall area calculator
Calculate four rectangular room walls, deduct openings, add waste and convert the area to complete packages.
How to use this calculator
How to measure
Measure room length, width and common wall height. Add the rectangular areas of doors and windows that will not be covered and enter their total once.
Worked example
A 4 × 3 × 2.5 m room has 35 m² gross wall area. Deducting 3 m² of openings leaves 32 m²; 10% waste gives 35.2 m².
Formula and purchasing method
gross = 2 × (length + width) × height; net = gross − openings; planned = net × (1 + waste/100); packages = ceil(planned ÷ package coverage).
Assumptions
- The room is rectangular and all walls share one height.
- Openings are already combined without overlap.
Limitations
- Sloped walls, niches and partial heights require separate calculations.
- The tool reports surface coverage, not material-specific fixing accessories.
FAQ
Should I subtract every window?
Subtract only surfaces that the chosen finish will not cover.
Can I use this for wallpaper or panels?
Yes when the product is sold by area and its package coverage is known; pattern matching belongs in the waste input.
Sources
Product-specific values must be copied from the exact current label or technical datasheet; linked examples document the method and its limits.
Calculation privacy
Calculations run locally. Form inputs and results stay in your browser.
How storage works and how to delete data