How to use this calculator
- Choose US customary or metric measurements.
- Enter the width and height of each wall.
- Enter optional combined door and window opening areas.
- Calculate gross wall area, deductions, and net wall area.
How the calculation works
Each wall width is multiplied by its height and the wall areas are added. Entered door and window areas are kept visible as separate deductions, then subtracted from gross area to produce net wall surface area.
Formula
Gross wall area = sum(wall width × wall height) Opening deductions = door area + window area Net wall area = gross area − opening deductions
Worked example
A 12 ft × 8 ft wall has 96 square feet of gross area. Deducting a 3 ft × 7 ft door, or 21 square feet, leaves 75 square feet of net wall area.
Project considerations
- Enter measured opening areas rather than assumed door or window sizes.
- The result is surface area only and does not estimate paint, drywall, insulation, wallpaper, or waste.
- For partial-height or irregular walls, divide the surface into non-overlapping rectangles.
Frequently asked questions
Should every opening be deducted?
Enter only the door and window areas you want removed from the gross wall surface.
Does this estimate materials?
No. It provides gross and net wall area that can be carried into a material-specific calculator.