Siding Calculator
Estimate siding squares for exterior walls.
Siding is sold by the 'square' (100 ft²). Estimate how many you need.
How the Math Works
The Siding Calculator uses a straightforward mathematical formula to estimate materials: squares = area × (1 + waste) ÷ 100. Here, 'area' represents the total square footage of your home's exterior walls, while 'waste' is a percentage factor accounting for cuts, overlaps, and damaged pieces. Multiplying by (1 + waste) increases the base area by the waste percentage, then dividing by 100 converts it to 'squares' — a standard industry unit where one square equals 100 square feet of siding material.
Practical Applications
To use this calculator practically, first measure each wall's height and length, then multiply these dimensions to get individual wall areas. Add all wall areas together to find your total surface area. Next, determine an appropriate waste factor — typically 5-15% depending on your home's complexity, roofline, and window/door cutouts. Enter these values into the formula to calculate exactly how many squares of siding to purchase, ensuring you order enough material to complete the job without excessive leftover inventory.
Day-to-Day Use
This calculation is essential for homeowners planning a siding project because it directly impacts your budget and project timeline. By accurately estimating materials upfront, you avoid costly trips to the supplier for additional supplies mid-project or expensive delays waiting for deliveries. The calculator helps you compare siding prices per square foot across different materials, understand true costs per square foot of finished wall, and communicate confidently with contractors about material quantities and pricing.
Worked example
1,200 ft² + 10% → 13.2 squares.
FAQ
Subtract windows?
For large openings, yes; small ones are usually left in as allowance.