Should I subtract doors and windows for paint?

Yes — subtract doors and windows from the wall area when calculating paint, plaster, or render needs. Do NOT subtract them for wallpaper or wall tiles, as you typically cover the full wall and cut around openings. The calculator shows both gross and net area so you can use the right number.

What if my room isn't rectangular?

For L-shaped or irregular rooms, break them into rectangular sections and add each as a separate 'room' in the calculator. The top-down layout view will display them side by side.

Does this work for sloped ceilings or attic rooms?

This calculator assumes standard rectangular rooms with vertical walls. For sloped ceilings, calculate the sloped wall area separately (treat it as a triangle) and add it manually. For very complex rooms, use a laser measure and a sketch.

Wall Area Calculator

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Add rooms with dimensions, subtract doors and windows, and get the exact paintable or tileable wall area. Per-room breakdown and a top-down layout view help you visualize the space.

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Add each room to calculate total paintable wall area

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How to use Wall Area Calculator

Click '+ Add Room' for each room and enter its name, width, length, and height in meters.
Add doors and windows using the preset buttons (+ Door, + Window) or + Custom for other openings.
Review the per-room wall area shown below each room card.
Click Calculate Totals to see the combined area across all rooms with paint/coverage estimates.

What is Wall Area Calculator?

For each room, the calculator computes the total wall area as 2 × (width + length) × height — the four walls. Door areas, window areas, and any custom openings (arches, pass-throughs, fireplaces) are subtracted to give you the net paintable or tileable area.

Standard door and window presets save time. The top-down layout view shows all rooms to relative scale with wall outlines and opening markers. Use the gross wall area (without deductions) for wallpaper, tiles, or insulation that cover openings. Use the net area for paint, plaster, or render that does not cover openings.

FAQ

Should I subtract doors and windows for paint?: Yes — subtract doors and windows from the wall area when calculating paint, plaster, or render needs. Do NOT subtract them for wallpaper or wall tiles, as you typically cover the full wall and cut around openings. The calculator shows both gross and net area so you can use the right number.
What if my room isn't rectangular?: For L-shaped or irregular rooms, break them into rectangular sections and add each as a separate 'room' in the calculator. The top-down layout view will display them side by side.
Does this work for sloped ceilings or attic rooms?: This calculator assumes standard rectangular rooms with vertical walls. For sloped ceilings, calculate the sloped wall area separately (treat it as a triangle) and add it manually. For very complex rooms, use a laser measure and a sketch.

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Last updated: 2026-06-05

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