Siding Calculator
Estimate siding squares and panels from wall area, openings, panel coverage and waste.
Calculate your estimate
Planning estimate only. Verify manufacturer specifications, local codes and project measurements.
Measure siding coverage before counting panels
- Measure each wall face in square feet and add the areas. Break gable ends into triangles rather than treating the entire elevation as a rectangle.
- Add the area of doors and windows you intend to deduct. Enter the total as openings, using the same square-foot unit as the wall area.
- Enter the exposed coverage of one panel and your chosen waste percentage, then select Calculate. Coverage must reflect overlap or interlocking profiles.
Siding Calculator: formula and assumptions
Net area = wall area − openings. Order area = net area × (1 + waste ÷ 100). Panels = order area ÷ panel coverage, rounded up; siding squares = order area ÷ 100.
Worked calculation
1,200 − 180 = 1,020 ft². With 10% waste: 1,122 ft², requiring 141 panels at 8 ft² per panel, or 11.22 siding squares.
What this estimate includes
Use actual exposed panel coverage, not nominal dimensions. Openings may equal the wall area for a zero net estimate, but cannot exceed it. Trim, starter strips and fasteners are excluded.
Planning details that change the estimate
Keep different siding products and wall elevations in separate estimates when panel coverage or cutting patterns differ. Large openings reduce installed area, but the surrounding cuts may not produce reusable pieces. Check whether a supplier sells individual panels, cartons or full squares before turning the estimate into an order. The calculator rounds panel quantity up; it does not round your order to full cartons.
Siding Calculator FAQs
What is a siding square?
One siding square represents 100 square feet of coverage. It is an area unit, not a count of panels or cartons.
Should I deduct every window and door?
Deduct only the opening area you want excluded. An area deduction does not account for the cutting losses around each opening; consider those when choosing waste.
Why must I use exposed panel coverage?
Nominal length times width can overstate installed coverage when panels overlap. Use the product’s stated effective coverage.
Does this include starter strips and corners?
No. Starter strips, corner pieces, J-channel, trim, housewrap and fasteners need separate takeoffs.
Continue planning this project
Use the Square Footage Calculator to total wall faces. Estimate a painted exterior separately with the Paint Calculator; use the Wall Stud Calculator only when the project also includes framing.
RESULTS