Room & Measurement

Wall Area Calculator

Calculate multi-wall gross and net surface area with door and window deductions for painting, tiling, or wallpapering.

Individual Walls

Add or remove wall partitions

Width (ft)

Height (ft)

Width (ft)

Height (ft)

Width (ft)

Height (ft)

Width (ft)

Height (ft)

Door & Window Deductions

Doors Count

Windows Count

Net Wall Area Summary

Square footage and metric meters

Net Paintable / Tiling Area

424 sq ft

39.39 m² metric equivalent

Gross Combined Wall Area:468 sq ft

Openings Deducted:−44 sq ft

Estimated Paint Needed (2 coats):~3 Gallons

Estimated Wallpaper Rolls:~9 Rolls

Per-Wall Gross Dimensions:

Wall 1 (14×9 ft):126 sq ft

Wall 2 (12×9 ft):108 sq ft

Wall 3 (14×9 ft):126 sq ft

Wall 4 (12×9 ft):108 sq ft

Net wall area is 424 sq ft (39.4 m²) across 4 walls, deducting 1 doors and 2 windows.

How It Works & Calculation Formula

Formula Summary: Net Wall Area = Σ(Wall Width × Height) − Σ(Door Openings + Window Openings).

Step-by-Step Calculation:

Enter individual wall width and height dimensions.
Calculate gross area for each wall: Width × Height.
Calculate opening areas: (Door Count × Door Area) + (Window Count × Window Area).
Subtract total opening area from gross wall area to obtain net paintable wall surface.
Convert results accurately between Square Feet and Square Meters.

Worked Example Calculation

Sample Inputs:

Wall 1:14 ft × 9 ft
Wall 2:12 ft × 9 ft
Wall 3:14 ft × 9 ft
Wall 4:12 ft × 9 ft
Doors:1 (36"×80")
Windows:2 (36"×48")

Expected Output:

Gross wall area: 468.0 sq ft. Openings deducted: 44.0 sq ft. Net wall area: 424.0 sq ft (39.4 m²).

Practical Tips & Trade Guidelines

For vaulted or cathedral ceilings, calculate the rectangular base wall and the triangular gable area separately.
Net wall area calculations are critical for accurate ordering of paint, wood paneling, shiplap, and acoustic wall panels.
Record your room wall measurements in a home notebook for future decorating and renovation projects.
Double-check that baseboard and crown molding trims are accounted for if planning full-height wainscoting.

Frequently Asked Questions

Add the lengths of all 4 walls to get the total perimeter, multiply by the ceiling height for gross area, then subtract the area of doors and windows.

Important Renovation Notice

Calculations are mathematical estimates based on standard trade conventions. Always field-verify room measurements, examine packaging labels, and check with a licensed contractor before purchasing materials or starting installation.