Siding Calculator
Work out the squares of siding and trim your walls need.
What you'll need to order
- siding panels
- house wrap
- J-channel
- corner posts
- starter strip
Prices vary by region and haul distance. Get quotes from at least two local suppliers.
How this calculator works
squares = (perimeter × height − openings) ÷ 100 × 1.10
A siding square covers 100 sq ft, the same unit roofers use. Only deduct openings over 10 sq ft — the offcuts around small windows are rarely reusable, so counting them as solid wall is more accurate.
Worked example
With wall perimeter 140 ft, average wall height 9 ft, doors and windows 200 sq ft, this calculator returns 11.66 .
Waste allowance
The headline figure includes a 10% allowance for waste and over-ordering. The exact requirement is shown alongside it.
Siding squares by wall height
Figures below assume wall perimeter 140 ft × doors and windows 200 sq ft. Change any measurement in the calculator to get your own numbers.
| Average wall height | Squares to order | Net wall area (sq ft) | Corner and trim material (ft) |
|---|---|---|---|
| 8 ft | 10.12 | 920.0 | 134.0 |
| 9 ft | 11.66 | 1,060 | 142.0 |
| 10 ft | 13.20 | 1,200 | 150.0 |
| 12 ft | 16.28 | 1,480 | 166.0 |
| 16 ft | 22.44 | 2,040 | 198.0 |
| 20 ft | 28.60 | 2,600 | 230.0 |
A 140 ft perimeter with 200 sq ft of windows and doors deducted. A two-storey house is usually 18 to 20 ft of wall height.
Siding for typical houses
| Job | Size | Squares to order | Material cost |
|---|---|---|---|
| Small bungalow | 100 ft × 9 ft × 130 sq ft | 8.47 | $2,541 – $7,623 |
| Single-storey ranch | 156 ft × 9 ft × 220 sq ft | 13.02 | $3,907 – $11,722 |
| Two-storey colonial | 140 ft × 18 ft × 380 sq ft | 23.54 | $7,062 – $21,186 |
| Detached garage | 96 ft × 10 ft × 90 sq ft | 9.57 | $2,871 – $8,613 |
| Large two-storey | 200 ft × 19 ft × 500 sq ft | 36.30 | $10,890 – $32,670 |
Perimeter is the distance around the whole building at ground level. Gable ends add area that this figure does not include — treat each gable as a triangle and add half its base times its height.
Cost range uses $300–$900 per square (100 sq ft) for material only.
What does siding cost per square?
Material typically runs $300 to $900 per square (100 sq ft). Installed, including house wrap and trim. Vinyl sits at the bottom of that range, fibre cement in the middle, and engineered wood or cedar at the top.
What moves the price:
- Material — vinyl, fibre cement, engineered wood and cedar span a three-fold range
- Tear-off and disposal of the existing siding
- Wall height: anything above one storey needs staging
- Trim complexity around windows, corners and rooflines
- Whether sheathing repairs are found once the old siding is off
Prices are US averages and move with fuel, season and haul distance. Always get two local quotes before budgeting.
Siding materials compared
| Type | Typical life (years) | Notes |
|---|---|---|
| Vinyl | 30.00 | Cheapest installed, never needs painting |
| Engineered wood | 30.00 | Wood look, needs repainting every 10 to 15 years |
| Fibre cement | 50.00 | Heavy, fire-resistant, the premium mainstream choice |
| Cedar bevel | 40.00 | Requires regular staining or painting |
| Brick veneer | 100.0 | Not siding as such; structural support required |
| Stucco | 60.00 | Needs a properly detailed drainage plane behind it |
Life expectancy assumes correct installation and a working drainage plane. Most siding failures are water management failures, not material failures.
Frequently asked questions
How do I measure my house for siding?
Measure the perimeter at ground level and multiply by wall height, then deduct window and door area. Add each gable separately as half its base times its height.
How much does it cost to side a house?
Vinyl runs $300 to $450 per square installed, fibre cement $500 to $800. A typical 25 square house therefore lands between $8,000 and $20,000 depending on material.
How many square feet in a square of siding?
One hundred. Siding is ordered in squares the same way roofing is, and a box of vinyl typically covers two squares.
Can new siding go over old?
Vinyl can go over sound wood siding with furring, but it is rarely a good idea. You cannot inspect the sheathing, the wall loses drying capacity, and any hidden rot keeps going.
How many squares of siding do I need?
Multiply the wall perimeter by the average height, subtract large openings, divide by 100 and add 10%. A typical 140 ft perimeter house with 9 ft walls needs about 12 squares.
Should I deduct windows and doors?
Only those over 10 sq ft. The cut pieces around small openings almost never fit anywhere else, so treating them as solid wall gives a more realistic order.
How much waste should I allow on siding?
Ten percent for a simple rectangular house, and 15% where there are gables, dormers or many corners. Gable ends in particular generate angled offcuts that cannot be reused.
Do I need house wrap under siding?
Yes, in virtually all jurisdictions. House wrap is the drainage plane that gets bulk water back out of the wall. Siding is a rain screen, not a waterproof layer, and always leaks somewhere.