Siding Calculator
Calculate how many squares of siding you need.
Enter wall dimensions, windows, and doors to get an accurate material estimate.
Exterior siding material is estimated by calculating the net wall area to be covered, then converting that into the units in which siding is sold.
Net wall area formula:
Net Area = Total Wall Area − (Windows Area + Doors Area)
Total Wall Area = Perimeter × Wall Height
Siding is sold in “squares”:
1 square = 100 ft² of coverage
Squares Needed = Net Area / 100
Waste factor by siding type:
- Horizontal lap siding: add 10–15% for cuts and overlap
- Vertical board and batten: add 8–12%
- Shingles / shakes: add 15–20% (irregular cuts)
- Fiber cement panels: add 10%
Worked example:
House perimeter: 140 ft. Wall height: 9 ft. Two windows (each 15 ft²), three doors (each 20 ft²).
Total Wall Area = 140 × 9 = 1,260 ft²
Deductions = (2 × 15) + (3 × 20) = 30 + 60 = 90 ft²
Net Area = 1,260 − 90 = 1,170 ft²
Base squares = 1,170 / 100 = 11.7 squares
With 12% waste: 11.7 × 1.12 = 13.1 → order 14 squares
Approximate material costs per square (2025–2026):
| Material | Cost per Square |
|---|---|
| Vinyl siding | $80–$150 |
| Engineered wood | $150–$250 |
| Fiber cement | $200–$350 |
| Cedar shingles | $300–$500 |
| Brick veneer | $700–$1,200 |
Always order one full square extra as a reserve for future repairs — dye lots change between production runs.