What this calculator does
The vinyl siding calculator estimates how many siding “squares” you need to cover your home’s exterior, after subtracting doors and windows and adding a waste allowance.
The formula
Gross wall area is your total wall perimeter multiplied by average wall height. Subtracting the combined area of doors and windows gives net area that actually needs siding. Siding is priced in industry-standard “squares,” where one square covers 100 square feet, so net area is increased by your waste percentage (to cover cuts, corners, and mistakes) and then divided by 100.
This is a general estimate for planning purposes. Complex rooflines, multiple stories, and trim details can change actual material needs, so confirm final quantities with your siding supplier.
Last reviewed August 2026