Siding Square Footage Calculator
Estimate the amount of siding materials needed for your project including waste factors.
Estimation Results
How to Calculate Siding for Your Home
Upgrading your home's exterior with new siding is one of the most effective ways to boost curb appeal and energy efficiency. However, ordering the correct amount of material is vital to avoid project delays or expensive overages. Siding is typically sold by the "Square," which represents 100 square feet of coverage.
Step-by-Step Measurement Guide
- Measure Height and Width: Measure the length of each wall from corner to corner. Then, measure the height from the bottom of the old siding to the eave.
- Subtract Openings: Most standard windows are approximately 12–15 square feet, and standard doors are about 20–21 square feet. Subtracting these prevents you from over-ordering.
- The Gable Math: For triangular gables, measure the base width and the height to the peak. Multiply (Base x Height) and divide by 2 to get the square footage of the triangle.
Understanding the Waste Factor
No siding project uses 100% of the material ordered. You will always have scraps from cuts around windows, doors, and rooflines. For a standard rectangular ranch-style home, 10% is usually sufficient. If your home has multiple stories, dormers, or complex gables, a 15% or 20% waste factor is highly recommended.
Example Calculation
Imagine a wall that is 40 feet long and 10 feet high. That's 400 gross square feet. If you have two windows (15 sq ft each) and one door (20 sq ft), your net area is 400 – 30 – 20 = 350 sq ft. Adding a 10% waste factor (35 sq ft) brings your total to 385 sq ft. Since siding is sold in squares, you would need to purchase 3.85 squares, which usually means rounding up to 4 full squares of material.