What does this tool do?
Siding is ordered by the area it covers, so the wall area minus openings is divided by the coverage of one panel or plank. A 10% waste allowance covers corners, gables and cuts around openings.
The Formula
Panels = ⌈(Wall length × Height − Openings) × 1.10 ÷ Coverage per panel⌉Frequently Asked Questions
How much siding waste should I allow?
10% is normal for straight walls, and 15% is safer for gables, corners and diagonal cuts.
Do I subtract windows and doors?
Yes, subtract their area to avoid over-ordering, but keep a little extra because offcuts around openings are often unusable.