Siding Calculator
Measure each wall section and subtract openings. Carton coverage must come from the selected product because exposure and packaging vary.
How to use this calculator
Add each rectangular, triangular, or trapezoidal wall section.
Subtract doors, windows, and other uncovered openings.
Enter carton coverage and review the 10% default allowance.
Formula
Order area = (gross wall area − openings) × (1 + allowance). Squares = order area ÷ 100 ft². Cartons = ceil(order area ÷ carton coverage).
Worked example
A net 1,500 ft² facade with 10% extra needs 1,650 ft², equal to 16.5 siding squares.
Assumptions and limits
- One siding square equals 100 ft².
- Default extra material is 10%.
- Overlap, exposure, corner accessories, and carton coverage depend on the product.
Sources
Related calculators
Frequently asked questions
What is a square of siding?
A siding square is a coverage unit equal to 100 square feet; it is not a 10 ft × 10 ft physical panel.
Can I use metric and US customary units in the Siding Calculator?
Yes. Unit changes convert the same canonical measurement; they do not reinterpret or round your original value.
When does the calculator round?
The calculation keeps full precision internally and rounds only the displayed result. Whole packages are rounded up at the final step.
Last updated · formula-v1 · content-2026-08-14 · Trusty Calculator Editorial Team