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Wall area calculator

Measure in

Room length

Room width

Wall height

Doors

Windows

Net wall area 32.28 m²

Perimeter × 2.4, less 1 door(s) and 2 window(s)

Gross wall area 36.96 m²

Openings deducted 4.68 m²

Net area 347.5 ft²

Perimeter 15.4 m

Door 1.8 m² · window 1.44 m² deducted

Wall area is the room perimeter times the wall height. Deduct 1.8 m² for each standard door and about 1.44 m² for each window. A 4.5 × 3.2 m room with 2.4 m walls has 36.96 m² gross, and 32.3 m² after one door and two windows.

How to calculate wall area

1 Enter the room dimensions, or switch to a single wall.

2 Set the wall height from finished floor to ceiling.

3 Count doors and windows — each is deducted at a standard size.

4 Use the net figure for paint, and the gross for plasterboard.

Which figure you use depends on the material. Paint and wallpaper follow the net area, because you genuinely do not cover a window. Plasterboard and insulation follow the gross area, because sheets are cut around openings and the offcut is usually scrap. Skirting and coving follow the perimeter minus the door widths. Using one number for all three is how a materials list ends up simultaneously over-ordering paint and under-ordering board.

Questions

How do I calculate wall area? −

Add the four wall widths for the perimeter, multiply by the height, then deduct doors and windows.

What size is a standard door for deduction? +

Should I deduct windows for plasterboard? +

How do I handle a sloping ceiling? +

Does wall area include the ceiling? +

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