Siding Calculator (Metric)
Enter your wall perimeter, height, gable area, and openings to get the squares of siding you need.
What your result means
Squares is your order quantity, since siding is sold and priced by the square (9.3 m² each), and it already has waste built in. Round up to whole squares when you order. Corner posts, trim, and starter strip get figured separately.
How to use this calculator
- Measure each exterior wall length and add them up (the perimeter).
- Use average wall height (8-3 m typical).
- Calculate gable area: for each triangular gable, area = (base x height) / 2.
- Count doors and windows.
- Use 10% waste for boxy homes, 15% for complex shapes.
- Read squares needed (1 square = 9.3 m², the standard siding order unit).
The formula
Wall area is perimeter times height. Add the gable area, subtract 2 m² per door and 15 per window for the net area, add your waste percentage, then divide by 100 to get squares.
Worked example
Say you've got a 30 by 9.1 m house with 2.7 m walls, so a 36.6 m perimeter. Two gables, each about 5.2 m², add 10.4 m². With 2 doors, 8 windows, and 10% waste: 1,7.4 m² of walls plus 112 of gables is 1,192 gross, minus 162 for the openings leaves 1,030 net, and 1,133 with waste, which rounds to 11.3 squares.
Siding cost by material (installed)
| Material | Installed cost (per sq ft) |
|---|---|
| Vinyl | $4 – $7 |
| Fiber cement | $7 – $15 |
| Wood | $8 – $15 |
| Brick | $15+ |
Tips & gotchas
- Siding is sold in squares, where one square is 9.3 m². Order whole squares.
- Use 10% waste on a simple boxy house, 15% on one with lots of windows, dormers, or odd angles.
- Gable ends are triangles: area is base times height divided by 2.
- A standard door counts as 2 m², a standard window as 15.
- Corner posts and trim are separate. Figure those on their own.
Frequently asked questions
What is a "square" of siding?
9.3 m². It's the standard unit for ordering and pricing siding.
How much siding do I need for a 2,0 m² house?
Usually 20 to 25 squares, depending on the shape and how many openings it has.
How much does siding installation cost?
Roughly $4 to $7 a square foot installed for vinyl, $7 to $15 for fiber cement, $8 to $15 for wood, and $15-plus for brick.
Should I include the gables in siding calculations?
Yes, gable ends usually get sided too. There's a gable-area input for exactly that.
How do I measure a gable triangle?
The base is the gable width and the height runs from the wall up to the ridge peak. Area is base times height divided by 2.
Related calculators
Estimates only — see our full disclaimer.