Wall Square Footage Calculator

Find net wall area after subtracting openings.

Wall length

Wall height

Openings area (doors/windows)

Net wall area 0

Gross area 1

Formula: net = length × height − openings

Step-by-step with your numbers:

1. Values used:

2. Wall length = 1

3. Wall height = 1

4. Openings area (doors/windows) = 21

6. Net wall area = 0

7. Gross area = Wall length x Wall height = 1 x 1 = 1

Did we solve your problem today?

Find the paintable/coverable wall area after removing windows and doors.

The math behind it

net area = length × height − total openings area.

20×8 ft wall minus 21 ft² of openings → 139 ft².

Standard door?

About 21 ft² (3 × 6.7 ft); a typical window ~12–15 ft².