Does the calculator account for multiple doors and windows?

Yes. You can add as many doors and windows as needed. Each opening is listed individually and subtracted from the gross wall area.

Should I add extra area for paint waste?

Most painters add 10–15% to the net area when buying paint to account for uneven surfaces, multiple coats, and cutting-in waste. The tool shows the net area; apply your own waste factor before purchasing.

What units does the calculator use?

You can choose between feet and meters. All inputs and outputs respect the selected unit. For tiles or wallpaper, convert the result to square yards or square meters as needed.

How is total wall area calculated?

For a rectangular room, total wall area = 2 × (length + width) × height. Openings (doors, windows) are subtracted to give net area.

Can I use this for non-rectangular rooms?

The calculator assumes a rectangular room. For L-shaped or irregularly shaped rooms, split the space into rectangular sections, calculate each separately, and sum the results.

Is the ceiling area included?

No. This tool focuses on vertical wall surfaces only. Use a separate ceiling area calculator if you need that measurement.

Wall Area Calculator

Calculate net wall area for painting or tiling by entering room dimensions and subtracting doors and windows.

Unit System

Room Dimensions

Length (ft)

Width (ft)

Height (ft)

Doors & Windows

optional

Type

Width

Height

Enter room dimensions and click Calculate

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Summary

The Wall Area Calculator helps homeowners, painters, and contractors determine the exact net surface area of room walls. By entering the room length, width, and height, the tool computes the total wall area and then subtracts the area occupied by doors and windows. The result is the net area you actually need to paint, tile, or wallpaper.

How it works

Enter the room dimensions: length, width, and ceiling height.
The tool computes the total perimeter wall area (2 × (length + width) × height).
Add any doors and windows by specifying their width and height.
Each opening is subtracted from the total wall area.
The net area is displayed instantly, along with a breakdown of deductions.

Use cases

Estimating how much paint or primer to purchase for a room.
Calculating the number of tiles needed to cover bathroom or kitchen walls.
Planning wallpaper quantities before ordering rolls.
Generating material takeoffs for construction or renovation bids.
Comparing painting cost estimates between rooms of different sizes.
Accounting for multiple doors and windows in an open-plan space.

Frequently Asked Questions

Last updated: 2026-05-29 · Reviewed by Nham Vu