Wall Area Calculator
The paintable and paperable wall area of a room, with doors, windows and a waste allowance taken off.
At a glance
- What you enter
- Room length, Room width, Wall height, Doors to deduct, Windows to deduct, Extra wall area to add, Include the ceiling, Waste allowance
- What you get
- Net wall area, Net wall area, Gross wall area, Gross wall area, Area of the openings, Openings as a share of the wall, Ceiling area, Ceiling area, Total area before waste, Area added by the waste allowance, Area to allow for, Wall area per square metre of floor
- Formula shown
- Yes, every step, right below your results.
- Cost and privacy
- Free, no account needed, and nothing you type is stored.
See worked examples ↓ Read the FAQ ↓ Share this calculator ↓
Results are estimates for general information only, always verify with a professional or official source before acting on them.
How to use the Wall Area Calculator
- 1 Enter Room length (m)
- 2 Enter Room width (m)
- 3 Enter Wall height (m), Floor to ceiling, or floor to the picture rail if only the lower band is being decorated.
- 4 Enter Doors to deduct, About 1.9 square metres each, both faces.
- 5 Enter Windows to deduct, About 1.4 square metres each.
- 6 Enter Extra wall area to add (sq m), Chimney breasts, alcoves or a wall that is not part of the rectangle. Add it here rather than guessing.
- 7 Enter Include the ceiling, Ceiling paint is a different product, so the area is reported separately as well.
- 8 Enter Waste allowance (%), Five percent for paint, ten for wallpaper or paneling where whole drops can be lost.
- 9 Press Calculate. You get Net wall area, Net wall area, Gross wall area, Gross wall area, Area of the openings, Openings as a share of the wall, Ceiling area, Ceiling area, Total area before waste, Area added by the waste allowance, Area to allow for, Wall area per square metre of floor, and every intermediate step stays visible under "How is this calculated?"
- 10 Change one number at a time to see what moves the result, that is usually the most useful thing a calculator can tell you.
Worked examples
Real numbers run through this calculator. Open any example to load it into the form above and change it.
A 4 by 3 metre room, no ceiling
One door, one window, five percent waste.
You enter
- Room length
- 4 m
- Room width
- 3 m
- Wall height
- 2.40 m
- Doors to deduct
- 1
- Windows to deduct
- 1
- Extra wall area to add
- 0 sq m
- Include the ceiling
- No
- Waste allowance
- 5%
You get
- Net wall area
- 30.30 sq m
- Net wall area
- 326.15 sq ft
- Gross wall area
- 33.60 sq m
- Gross wall area
- 361.67 sq ft
- Area of the openings
- 3.30 sq m
- Openings as a share of the wall
- 9.8%
- Ceiling area
- 0.00 sq m
- Ceiling area
- 0.00 sq ft
- Total area before waste
- 30.30 sq m
- Area added by the waste allowance
- 1.52 sq m
- Area to allow for
- 31.82 sq m
- Wall area per square metre of floor
- 2.53
33.6 square metres gross, 30.3 square metres net, 31.8 square metres to allow for with the waste.
A period living room with a chimney breast
A 5 by 4 metre room at 2.8 metres, two windows, one door, a chimney breast adding 1.5 square metres.
You enter
- Room length
- 5 m
- Room width
- 4 m
- Wall height
- 2.80 m
- Doors to deduct
- 1
- Windows to deduct
- 2
- Extra wall area to add
- 1.50 sq m
- Include the ceiling
- Yes
- Waste allowance
- 10%
You get
- Net wall area
- 45.70 sq m
- Net wall area
- 491.91 sq ft
- Gross wall area
- 50.40 sq m
- Gross wall area
- 542.50 sq ft
- Area of the openings
- 4.70 sq m
- Openings as a share of the wall
- 9.3%
- Ceiling area
- 20.00 sq m
- Ceiling area
- 215.28 sq ft
- Total area before waste
- 65.70 sq m
- Area added by the waste allowance
- 6.72 sq m
- Area to allow for
- 73.92 sq m
- Wall area per square metre of floor
- 2.29
The tall ceiling alone adds nearly 6 square metres over a modern room of the same footprint, and the chimney breast adds another 1.5.
A small bedroom in wallpaper
A 3 by 2.5 metre room at 2.4 metres with one door, no windows to deduct, ten percent waste.
You enter
- Room length
- 3 m
- Room width
- 2.50 m
- Wall height
- 2.40 m
- Doors to deduct
- 1
- Windows to deduct
- 0
- Extra wall area to add
- 0 sq m
- Include the ceiling
- No
- Waste allowance
- 10%
You get
- Net wall area
- 24.50 sq m
- Net wall area
- 263.72 sq ft
- Gross wall area
- 26.40 sq m
- Gross wall area
- 284.17 sq ft
- Area of the openings
- 1.90 sq m
- Openings as a share of the wall
- 7.2%
- Ceiling area
- 0.00 sq m
- Ceiling area
- 0.00 sq ft
- Total area before waste
- 24.50 sq m
- Area added by the waste allowance
- 2.45 sq m
- Area to allow for
- 26.95 sq m
- Wall area per square metre of floor
- 3.27
About 25 square metres of wall, then about 27.5 with the waste, which is where the wallpaper calculator takes over.
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