Siding Calculator

How to use this calculator

1. 01Choose a mode: wall dimensions, total wall area, or gable wall.
2. 02Enter the wall size or total area. For repeated walls, use the number of same-size walls field.
3. 03Enter the total openings area for windows, doors, and other areas that will not receive siding.
4. 04Add a waste percentage. Ten percent is a common starting point for straight walls; use more for complex layouts.
5. 05Add coverage per panel and price per square foot if you want piece count and cost estimates.

Understanding the math

Siding takeoff starts with wall area. For a rectangle wall, multiply width by height, then multiply by the number of matching walls. For a gable wall, use base width times gable height divided by 2. Subtract openings, add waste, then divide by 100 to convert square feet into siding squares. If you enter coverage per panel or piece, the calculator divides the order area by that coverage and rounds up.

Gross area        = wall width × wall height × wall count
Gable area        = base width × gable height / 2
Net siding area   = gross area - openings
Order area        = net area × (1 + waste / 100)
Siding squares    = order area / 100
Panels or pieces  = order area / coverage per piece

For four 40 ft × 9 ft walls with 150 sq ft of openings and 10 percent waste: gross area is 40 × 9 × 4 = 1,440 sq ft. Net siding area is 1,440 - 150 = 1,290 sq ft. Order area is 1,290 × 1.10 = 1,419 sq ft. That equals 14.19 siding squares, so you would round up to 15 squares when ordering.

Siding quick reference

Use these common siding conversions when checking the calculator results.

Frequently asked questions

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