How do I calculate room square footage?

Measure the room length and width in feet, then multiply length by width. For an L-shaped room, subtract the rectangular cut-out or split the room into rectangles.

Should I use floor area or wall area for paint?

Use floor area for flooring and ceiling area. For paint or wallpaper, use wall area and subtract doors and windows when appropriate.

Room Area Calculator

Calculate room square footage, perimeter, wall area, ceiling area and room volume from feet-based room dimensions.

Room shape

Room length

Room width

Room height

Room plan

Doors

Windows

Door size (in)

Window size (in)

Room square footage for remodeling

Room 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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