How do I calculate wall square footage?

Add the wall lengths to get perimeter, multiply by wall height, then subtract the square footage of doors and windows if the material does not cover them.

Do I subtract windows for paint?

Usually yes for a rough material estimate, but small openings are sometimes left in the estimate to cover touch-ups, texture and waste.

Wall Area Calculator

Calculate gross and net wall square footage for paint, wallpaper, panels or tile after subtracting doors and windows.

For a rectangular room with four walls, enter the room dimensions and subtract doors or windows. Add niches, returns, and trim areas separately when they also need finishing.

Room length

Room width

Wall height

Doors and windows

Door

Width (in)

Height (in)

Count

Window

Width (in)

Height (in)

Count

Waste factor (%)

Material estimate

Roll width (in)

Roll length (ft)

Pattern repeat (in)

Wall square footage for paint and wallpaper

Wall area calculators in the English SERP are practical measuring tools first. The primary answer is square footage, with optional waste, cost and metric conversions for shopping lists or estimates.

A r e a = L e n g t h \times W i d t h

For a rectangular room or surface, multiply the two dimensions measured in feet to get square feet.

For irregular rooms, split the surface into simple rectangles or use the L-shape mode, then add a waste allowance for cuts, layout and measurement error.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: May 29, 2026

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