Siding Panel Count Calculator

Calculate the number of siding panels needed for your project, accounting for openings and waste.

Total Wall Width (ft) Wall Height (ft) Number of Walls

Number of Windows Avg Window Width (ft) Avg Window Height (ft) Number of Doors Avg Door Width (ft) Avg Door Height (ft)

Panel Width (in) Panel Height (in) Panel Overlap / Exposure (in) Waste Factor (%)

Gross Wall Area = Wall Width × Wall Height × Number of Walls

Opening Area = (Number of Windows × Window W × Window H) + (Number of Doors × Door W × Door H)

Net Wall Area = Gross Wall Area − Opening Area

Effective Panel Width = Panel Width − Overlap

Panel Face Area = Effective Panel Width × Panel Height

Base Panels = Net Wall Area ÷ Panel Face Area

Total Panels = ⌈ Base Panels × (1 + Waste% ÷ 100) ⌉

All walls are assumed to have the same width and height. For irregular structures, calculate each wall separately and sum the results.
Panel overlap (also called "exposure") reduces the effective coverage width of each panel.
A waste factor of 10% is standard for straight runs; increase to 15–20% for diagonal or complex patterns.
Opening deductions follow the National Siding Contractors Association guideline of subtracting 100% of opening area for openings larger than 10 sq ft.
Panel dimensions should match manufacturer specifications (width and height in inches).
Results are always rounded up to the nearest whole panel to avoid shortages.
This calculator does not account for trim, corner pieces, or starter strips — order those separately.

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