Siding Calculator

One siding square equals 100 sq ft of finished wall, the same unit used for roofing. Vinyl, fiber cement, engineered wood, and metal panel siding are all priced and packaged per square because contractors estimate jobs in squares and bid materials at that scale. A 1,800 sq ft house wall area works out to 18 squares before waste. The calculator rounds up to the next whole square so you never come up short.

Use about 10 percent for vinyl on a straight rectangular house. Bump to 15 percent for fiber cement (it cracks more easily during cutting and handling), 10 to 12 percent for engineered wood, and 8 to 10 percent for metal panels that snap-lock with predictable cuts. Add another 5 percent on top for cut-up elevations with many gables, dormers, or angled walls, since each penetration creates an extra trim cut.

Materials only: vinyl runs $3 to $7 per sq ft, fiber cement (such as James Hardie) runs $5 to $12, engineered wood (such as LP SmartSide) runs $5 to $10, and metal (steel or aluminum panels) runs $4 to $9. Installation labor typically doubles the total cost. Premium textures, color, and trim packages push the high end of each range. Enter your supplier's price per sq ft to get a quick materials estimate from the calculator.

Gables are the triangular wall sections under a pitched roof, and a typical 30 ft wide house with a 4 ft gable rise adds 60 sq ft per end (0.5 x 30 x 4). Two gables add 120 sq ft, which is over a full square. Doors and windows go the other way: a standard 3 by 7 ft door subtracts 21 sq ft and a 3 by 5 ft window subtracts 15 sq ft. A house with 2 doors and 8 windows nets out 162 sq ft less siding (more than 1.5 squares), enough to change your order.

Vinyl is the most DIY-friendly: it snap-locks, cuts with tin snips, and forgives small layout mistakes. A confident homeowner can handle a single-story rectangular house in a long weekend. Fiber cement is heavy, requires special blades, and produces silica dust that needs respirators and dust control, so most homeowners hire it out. Engineered wood sits between the two. Metal panels need a brake for custom trim and tight tolerances at every corner. If your house has tall gables, multiple stories, or steep ladder work, hire a pro regardless of material.