Siding Calculator
Estimate siding square footage, siding squares, and cartons from wall dimensions, openings, waste, and the coverage printed on each carton.
Enter your measurements and calculate.
Example
1,440 sq ft gross walls minus 180 sq ft openings = 1,260 sq ft. At 10% waste, order about 1,386 sq ft, or 13.9 siding squares.
Sources & assumptions
Formulas on this page are direct geometry or business-math relationships. Product-specific coverage inputs are intentionally editable.
Last reviewed September 1, 2026. Defaults are starting points; product-specific inputs are editable wherever coverage varies.
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Common questions
What is a siding square?
100 square feet of siding coverage.
Do cartons always cover 200 sq ft?
No. Some common vinyl products do, but coverage varies by product.
Should I subtract windows and doors?
Yes for a more accurate net wall area.
From wall square footage to a safer material order
Start with net wall square footage after openings, add the selected waste allowance, then convert to siding squares or the carton coverage printed on the product. One siding square equals 100 square feet of coverage.
After you know the quantity, use the Material Buffer Optimizer to compare extra material against the expected cost of coming up short.