How Much Siding Do I Need?

Siding is priced and ordered in "squares" — 100 sq ft each — a holdover unit from traditional roofing and siding trades. Start with gross wall area (perimeter × height), subtract doors and windows, then divide by 100 and round up.

Don't forget gable ends on pitched-roof homes — they add real area that's easy to miss if you only measure the rectangular wall sections.

The Siding Calculator handles the opening subtraction and converts straight to squares needed.

Starter strips, J-channel, and corner posts are sold separately from the siding panels and aren't included in the squares-needed figure — budget for them as linear-foot trim items around every corner, window, and the base of the wall.