🏠 Siding calculation formula: Total wall square footage minus openings (windows/doors). One “square” of siding = 100 sq ft. Add 10% waste for cuts and overlaps.

💡 Pro tip: Measure each wall’s height and width separately. For gable walls, use triangle area formula: (Base × Height) ÷ 2. Always order 10-15% extra for waste and future repairs.