Siding Cost Calculator
Estimate siding squares and total material cost from wall area, openings to subtract, a waste allowance, and your price per square.
How to use this tool
- Measure each exterior wall (length x height) and total the areas.
- Subtract the area of doors and windows that won't be sided.
- Set a waste allowance (10% simple, 15%+ for many corners and gables).
- Enter your installed price per square (100 sq ft).
- Read the squares and the total material cost.
Price out a siding job. Enter the wall area, subtract doors and windows, add a waste allowance, and this tool gives you the squares and total material cost.
Formula
Siding, like roofing, is sold by the square (100 sq ft). Subtract openings, convert to squares, and add waste:
Net area = Wall area − Doors & windows
Squares = (Net area ÷ 100) × (1 + Waste%)
Total cost = Squares × Price per square
How it works
Exterior siding is estimated much like roofing: in squares, where one square equals 100 square feet of wall. We sum the gross wall area, subtract the area of doors and windows that won't be sided, then convert the net area to squares and apply a waste allowance. The waste covers the angled cuts around windows, doors, and gables, plus the overlap built into lap and shingle siding.
Ten percent is a reasonable allowance for a simple rectangular wall; houses with many corners, gables, and openings generate more off-cuts and warrant 15% or more. We multiply the resulting squares by your installed price per square, which lets you plug in a contractor's per-square quote or your own material cost directly.
The figure covers field siding only. Starter strip, J-channel, corner posts, soffit, fascia, house wrap, and trim are priced separately, and labor may be quoted per square or as a lump sum. Subtracting openings is a sensible default, but some installers order siding on gross wall area to guarantee enough material; if yours does, set the openings field to zero.
Worked example
1,600 sq ft of wall, 160 sq ft openings, 10% waste, $400/square
- Net area = 1,600 − 160 = 1,440 sq ft.
- Base squares = 1,440 ÷ 100 = 14.4 squares.
- Add 10% waste: 14.4 × 1.10 = 15.84 squares.
- Total cost = 15.84 × $400 = $6,336.
Total $6,336.00 | 15.84 squares | Net area 1,440.00 sq ft
Siding squares by net wall area (+10% waste)
| Net wall area | Base squares | With waste |
|---|---|---|
| 800 sq ft | 8.0 | 9 |
| 1,200 sq ft | 12.0 | 14 |
| 1,600 sq ft | 16.0 | 18 |
| 2,000 sq ft | 20.0 | 22 |
| 2,800 sq ft | 28.0 | 31 |
Key terms
- Square
- A unit of wall or roof area equal to 100 square feet. Siding is ordered and often priced per square.
- Net wall area
- Gross wall area minus the area of doors, windows, and other openings that will not be covered with siding.
- Waste allowance
- Extra material ordered to cover cuts around openings and corners plus the overlap of lap siding, typically 10-15%.
- Lap siding
- Horizontal boards or panels installed so each course overlaps the one below it, shedding water down the wall.
- J-channel
- Trim that receives and finishes the cut edges of siding around windows, doors, and the roofline.
Frequently asked questions
- How many squares of siding do I need?
- Total the wall area, subtract doors and windows, divide by 100 to get squares, then add about 10% for waste. A 1,600 sq ft wall with 160 sq ft of openings needs about 15.8 squares with 10% waste.
- How much does siding cost per square?
- Installed cost varies widely by material — vinyl is the most affordable, with fiber-cement and engineered wood higher. Enter your quoted or estimated price per 100 sq ft square.
- Should I subtract windows and doors?
- Subtracting openings gives a tighter material estimate. Some installers order on gross wall area to ensure enough material and cover waste; if so, set openings to zero and rely on the waste allowance.