Wall Area Calculator

Calculate the total wall area of a rectangular room, then deduct the area taken up by doors and windows to get the net surface that needs covering — the number you actually use for paint, wallpaper or tiling estimates.

Enter room dimensions

Units
Each door counts as 1.8 m² (20 ft²).
Each window counts as 1.5 m² (16 ft²).
Total area of any other openings you want to exclude.

Enter room dimensions, then press Calculate.

Wall area formulas

Perimeter = 2 × (length + width)

Gross wall area = perimeter × wall height

Net wall area = gross − doors − windows − other openings

Paint Calculator

Paint quantity with coats and coverage.

Square Footage Calculator

Floor or room area.

Frequently asked questions

Yes for accurate paint estimates — you don't paint glass or door frames. For wallpaper, many installers ignore small windows and factor the waste allowance instead, because cutting around openings creates offcuts anyway.

Break the room into rectangular sections and calculate each one separately. Add the perimeters of each section and multiply by wall height, then subtract openings. For L-shaped rooms, treat the space as the sum of two rectangles.