Siding calculator
How much siding do I need?
Estimate the number of siding pieces needed for exterior walls based on wall area and siding exposure.
Siding calculator
Siding calculator result
Siding types and exposure
- Vinyl siding: 4 inches exposure standard, varies by profile
- Wood lap siding: 4-6 inches exposure depending on board width
- Fiber cement: 4-5 inches exposure, typically 6.25 or 8.25 inch planks
- Board and batten: 8-12 inch board spacing
Add 10% for waste, cuts, and gable ends. For walls with many windows and doors, subtract the rough opening area before calculating.
Worked example
For example, for a 20×10 ft wall, 4-in exposure lap siding:
- Wall area = 20 × 10 = 200 sq ft
- Pieces needed = (200 × 12) ÷ (4 × 20) = 2400 ÷ 80 = 30 pieces
- Add 10% for waste, starter strips, and corners: 33 pieces
- Also order J-channel around windows, corner trim, and starter strip
Common mistakes
| Mistake | Why it matters |
|---|---|
| Not accounting for window and door trim | Subtract rough openings but add J-channel and corner trim to your materials list |
| Starting with a level course | The first course must be perfectly level — any tilt amplifies as you go up |
| Nailing too tight | Leave 1/32-in gap between nail head and siding to allow for thermal expansion |