Siding Calculator
Calculate how many siding panels you need for an exterior wall area.
Assumptions used in this calculation
- Waste covers openings and cuts: The waste percentage is assumed to account for material lost to cuts around doors/windows and corner trims, rather than those openings being subtracted from wall area directly.
- Panel coverage net of overlap: Assumes the coverage-per-panel figure you enter already reflects the panel's effective exposed coverage after any overlap with adjacent panels, check your product spec sheet for this number.
About this calculator
Exterior siding jobs generate more waste than an interior finish would, corners, gables, dormers and window trim all mean extra cuts, and underestimating that waste is a common reason siding projects come up short mid-installation. This calculator divides total exterior wall area by a single panel's effective coverage after adding a waste percentage for cuts and overlaps, rounding the result up to a whole panel since siding is bought by the panel, not a fraction of one. Enter your total wall area, a panel's coverage figure from its product spec sheet, and a waste allowance, and get a ready-to-order panel count instead of estimating cuts by eye across an entire exterior. Because homes with many corners, gables or dormers generate meaningfully more offcuts than a simple rectangular home, bumping the waste allowance from the 10% default up to 15-20% for a complex exterior avoids a frustrating mid-job shortfall.
Worked example
1,500 sqft exterior, 16 sqft panels, 10% waste
Result: ≈ 104 panels
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