Wall geometry
Wall area calculator
Add measured rectangular walls and openings to calculate gross, excluded and net wall area.
Wall geometry
Result
How net wall area is calculated
Add each rectangular wall, then assign every measured door, window or other rectangular opening to the wall from which it should be subtracted.
How to use it
- Add every wall once and enter its measured width and height.
- Add each physical opening once, enter its width and height, and select the correct wall.
- Review gross, excluded and net wall area before using the result in another calculation.
Formula
Net wall area = the sum of width × height for all walls − the sum of width × height for all assigned openings.
Example
A 4 m × 2.5 m wall has 10 m² gross area. Subtracting openings of 0.9 m × 2.1 m and 1.2 m × 1.2 m removes 3.33 m², leaving 6.67 m² net wall area.
Assumptions
- Walls and openings are rectangles, and each opening belongs to the selected wall.
- Openings are assumed not to overlap and each physical opening is entered only once.
Limitations
- The calculator does not know coordinates, orientation or the real placement of an opening.
- It cannot detect overlapping openings or the same physical opening entered twice.
- Perimeter, materials, waste, packages and prices are not calculated.
Wall area questions
Should I subtract doors and windows?
Add an opening when you do not want its area included. Enter each physical door or window once and assign it to the correct wall.
Can net wall area be zero?
Yes. If entered openings exactly equal gross wall area, zero is a valid geometry result. Material calculations normally require a positive area.