Siding Calculator
Estimate siding in 100-square-foot squares and individual lap-siding panels. Add gables, subtract doors and windows, and adjust exposure and waste.
How this calculator works
Gross wall and gable area is reduced by measured openings, then multiplied by the waste factor. Panel count uses stock length times visible course exposure.
Formula: order area = (wall area + gables − openings) × (1 + waste)
Worked example
Walls totaling 100 ft long by 8 ft high, plus a 50 ft² gable and minus 100 ft² of openings, leave 750 ft² net. With 10% waste, order 825 ft² or 9 squares.
Before you order
- Use actual exposure, not the full panel width.
- Measure each gable as base × height ÷ 2.
- Order trim, corners, starter strip, flashing and fasteners separately.