What does this tool do?
Wall area starts with room perimeter multiplied by ceiling height, then openings are deducted. This calculator applies standard allowances of 21 square feet per door and 15 per window.
The Formula
Wall area = 2 × (Length + Width) × Height − Doors × 21 − Windows × 15Frequently Asked Questions
How much area does a door or window take up?
A standard interior door is about 21 square feet and a standard window about 15. Oversized openings should be measured and deducted directly.
Do I need to subtract baseboards or trim?
No. Paintable wall area is usually measured to the trim. Trim is painted separately, so its area is not part of the wall figure.