Siding Calculator
Enter your gross wall area and openings to get the siding squares needed, in the industry-standard 100 sq ft unit.
This calculator gives an estimate for planning purposes only. Verify quantities and code requirements with a qualified professional before ordering materials or performing work.
How it's calculated
Net wall area
net area = gross wall area − windows & doors area
Subtract the total area of openings from the gross wall area — siding doesn't cover glass or door slabs.
Squares needed
squares = (net area × (1 + waste %)) / 100
Siding is sold by the "square" — 100 sq ft — the industry-standard coverage unit regardless of material or exposure width.
Squares needed by gross wall area (no openings subtracted, 10% waste)
| Gross wall area | Squares needed |
|---|---|
| 800 sq ft | 8.8 sq |
| 1,200 sq ft | 13.2 sq |
| 1,500 sq ft | 16.5 sq |
| 2,000 sq ft | 22 sq |
| 2,500 sq ft | 27.5 sq |
Skip the manual math on your next takeoff
Struvia reads your plans and pulls quantities like this automatically — upload a plan and see it measure a real takeoff.
Siding Calculator FAQ
What is a siding "square"?
A square equals 100 square feet of wall coverage. It's the standard unit siding is bid, ordered, and installed in, regardless of the specific product's panel or plank dimensions.
How much waste factor should I use for siding?
10% covers a straightforward wall with standard corners and openings. Increase it for complex elevations, dormers, or diagonal cuts.
Do I need to measure gables and dormers separately?
Include their area in your gross wall area total — triangular sections like gables just need length × height / 2 added to the rectangular wall area before running the calculator.