Siding calculator
Estimate how much exterior siding you need for vinyl, fiber cement, or wood panels. Enter house perimeter and wall height, add gable triangles, subtract openings, and apply a waste factor.
FAQ for this calculator
- What is a siding square?
- One square covers 100 square feet of wall area. Suppliers price and ship vinyl and fiber cement by the square.
- How much waste should I add?
- 10% is common for simple rectangular homes. Use 15% for dormers and bay windows, 20% for very complex layouts or inexperienced installers.
- How do I measure gables?
- For each triangular gable end, multiply base × height ÷ 2. Add all gable areas into the gable field.
- Does this work for all siding types?
- Yes—area math is the same for vinyl, fiber cement, engineered wood, and wood lap. Panel coverage and accessories vary by product line.
How to use the siding calculator
Siding is ordered in squares (100 sq ft). This tool computes net exterior area, adds your waste allowance, and rounds up to whole squares.
- Measure total exterior perimeter and average wall height.
- Add gable triangle areas and subtract doors and windows.
- Set waste—10% for simple boxes, 15–20% for dormers and many corners.
- Optionally enter cost per square for a material budget hint.
When to use this calculator
- Vinyl re-side on a rectangular ranch before ordering from the lumber yard.
- Fiber-cement takeoff with gable ends and garage door subtracted.
- Comparing 10% vs 15% waste on a house with bay windows.
Examples & walkthrough
- 130 ft perimeter, 10 ft walls, 150 sq ft gables, 200 sq ft openings, 10% waste → 1,375 sq ft → 14 squares.
- Smaller 80 ft perimeter, 9 ft height, no gables, 60 sq ft openings, 10% waste → about 6 squares.