Home Improvement

Siding Calculator

Calculate how much siding you need for your home.

Enter your total exterior wall area (minus doors and windows) to calculate how many "squares" of siding to order — the standard unit siding is sold in.

Enter a valid area.

Siding Squares Needed

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How to Use This Tool

  1. Measure the total area in square feet.
  2. Adjust the sq ft per square if your product differs from the default.
  3. Click Calculate to see how much you need, including a waste allowance.

The Coverage Formula

squares Needed = (Area × (1 + Waste %)) ÷ Coverage per Unit

This calculator adds your specified waste allowance to the raw area before dividing by coverage, ensuring you order enough to account for cuts, mistakes, and pattern matching.

Why Waste Allowance Matters

A 10% waste allowance is a common industry default, but complex layouts, diagonal patterns, or a room with many corners and cutouts may need a higher allowance (15-20%), while simple rectangular rooms may need less.

Frequently Asked Questions

How much waste allowance should I use?

10% is a common default for straightforward rectangular areas. Increase to 15-20% for complex layouts, diagonal installations, or rooms with many corners, alcoves, or obstacles.

What if my product's coverage rate is different?

Adjust the "Sq Ft per Square" field to match your specific product's coverage rate, found on the product packaging or manufacturer's specification sheet.

What is a "square" in siding terms?

A "square" is the standard unit siding contractors use, equal to 100 square feet of wall coverage — it's a convention borrowed from roofing.

This calculator is provided for general informational and estimation purposes only. Results should not be treated as professional financial, tax, legal, medical, or engineering advice. Always verify critical calculations with a qualified professional or official source before making decisions.