🏠 Siding Calculator
Estimate how much siding you need to cover your home’s exterior walls, accounting for windows, doors, and a waste allowance.
What this calculator does
The siding calculator estimates how much siding material you need to cover your home’s exterior walls, after subtracting window and door openings and adding a cutting waste allowance.
The formula
Gross wall area is your total wall length multiplied by wall height. Subtracting the combined area of windows and doors gives the net area that actually needs siding. A waste allowance (commonly 10%, more for hip roofs, dormers, or lots of corners) is added, and the result is also expressed in “squares” — the roofing and siding industry’s unit for 100 square feet of coverage.
This is a general material estimate. Corner posts, starter strips, and J-channel are calculated separately and vary by siding profile and manufacturer.