BuildersMeasures

Wall Area Calculator

Calculate the gross and net wall area for painting, plastering, rendering, tiling, wallpapering, insulation, and other wall-covering projects. Enter the wall dimensions, number of walls, openings, and waste allowance to get an area estimate in square metres or square feet.

Wall dimensions
Use this for several walls with the same length and height.
%
Useful when estimating paint, tiles, plaster, wallpaper, or similar materials.
Doors and windows
Net wall area with waste 0 m2
Gross wall area 0 m2
Door area 0 m2
Window area 0 m2
Total opening area 0 m2
Net wall area 0 m2
Waste allowance 0 m2
Planning note: The waste-adjusted figure is an estimating quantity for material planning. Actual material requirements vary according to surface condition, application method, cuts, breakage, pattern matching, overlaps, and project specifications.

How to Calculate Wall Area

For a simple rectangular wall, multiply the wall length by its height. If the project has doors or windows, calculate their areas separately and subtract them from the gross wall area.

Gross Wall Area = Wall Length × Wall Height × Number of Walls

Door Area = Door Width × Door Height × Number of Doors

Window Area = Window Width × Window Height × Number of Windows

Net Wall Area = Gross Wall Area − Door Area − Window Area

Planning Area = Net Wall Area × (1 + Waste ÷ 100)

The calculator converts imperial measurements into square metres internally, then displays the result in the measurement system selected by the user.

What Wall Area Do You Need?

Project Area to use Typical allowance
Painting Net wall area Allow for coats and product coverage separately
Plastering Net wall area Account for surface variation and thickness
Rendering Net wall area Account for surface condition and application losses
Wall tiling Net wall area Usually allow extra for cuts and breakage
Wallpaper Net wall area Pattern matching can increase waste
Insulation Net wall area Account for cuts and installation details

Material manufacturers and project specifications often provide their own coverage or waste recommendations. Use those figures when available.

Worked Example

Consider one wall measuring 6 m wide × 2.7 m high. It has one door measuring 0.9 m × 2.1 m and two windows measuring 1.2 m × 1.2 m.

Gross area = 6 × 2.7 = 16.20 m2

Door area = 0.9 × 2.1 = 1.89 m2

Window area = 1.2 × 1.2 × 2 = 2.88 m2

Net area = 16.20 − 1.89 − 2.88 = 11.43 m2

With a 10% allowance, the planning area becomes approximately 12.57 m2. This figure is useful when estimating the amount of a wall-covering material required for the project.

Common Wall Area Calculation Mistakes

  • Forgetting to multiply by the number of identical walls.
  • Using gross wall area when doors and windows need to be deducted.
  • Mixing metres with feet in the same calculation.
  • Forgetting that different walls often have different dimensions.
  • Ignoring waste when ordering tiles, wallpaper, insulation, or other materials.
  • Adding waste before deducting openings.
  • Assuming the calculated net area equals the exact amount of material required.

Wall Area Calculator FAQs

How do I calculate the area of a wall?
Multiply the wall length by the wall height. For multiple identical walls, multiply the result by the number of walls. Subtract doors and windows when you need the net wall area.
Do I subtract doors and windows from wall area?
Yes, when estimating a material applied only to the exposed wall surface. Subtract the area of doors and windows from the gross wall area to obtain the net area.
How do I calculate wall area in square feet?
Multiply the wall length in feet by the wall height in feet. The result is square feet. If your measurements are in metres, multiply square metres by 10.7639 to convert to square feet.
How do I calculate wall area in square metres?
Multiply the wall length in metres by the wall height in metres. The result is square metres. For multiple identical walls, multiply by the number of walls.
How much waste should I add to wall area?
The allowance depends on the material and installation method. Around 5% to 15% is often used for general estimating, while patterned wallpaper, tiles with complex cuts, and irregular surfaces might require a different allowance.
Does wall area include the ceiling?
No. Wall area and ceiling area are separate measurements. A ceiling is normally calculated from its length and width, while a wall uses length and height.
Can I use this calculator for painting?
Yes. Calculate the net wall area first, then use the paint manufacturer's coverage rate and the number of coats to determine the amount of paint required.