Construction
Siding Calculator
Enter your home's footprint, number of stories, gable ends, and openings to estimate net siding area, the number of squares (1 square = 100 sq ft), and boxes to order with a waste allowance.
Quick answer: Siding is measured in 100-sq-ft 'squares.' A two-story home on a 50×30 footprint needs roughly 16–18 squares after waste and openings.
- Wall perimeter160 ft
- Flat wall area2,880 sq ft
- Gable triangles+240 sq ft
- Windows & doors−216 sq ft
- Siding squares29.0
- Waste allowance (15%)+4.4 sq
- Squares to order33.4
- Boxes (≈2 squares each)17
One siding square covers 100 sq ft of wall. Uses an average 9 ft story height and an 18 sq ft deduction per opening. Actual material depends on profile, exposure, corner posts, J-channel, and starter strip.
How it works
1. Calculate wall area
Wall area is the perimeter × an average 9-ft story height × the number of stories. Each gable end adds a triangle roughly equal to half the wall width × an 8-ft rise.
2. Deduct openings
Subtract about 18 sq ft per window or door. The net area divided by 100 gives siding squares — the unit siding is sold and priced in.
3. Add waste
Siding wastes more than roofing because every corner and opening forces an off-length cut: 10% simple, 15% moderate, 20% complex. One box of double-4 vinyl covers about 2 squares.
Frequently asked questions
What is a siding square?
One siding square covers 100 square feet of wall. Siding is sold and priced by the square, so estimating your square count is the first step to a material order or a quote.
How much siding do I need for a 2,000 sq ft house?
It depends on the wall area, not the floor area. A two-story home on a 50×30 footprint has roughly 1,400+ square feet of wall before gables and openings — about 16–18 squares with waste. Use the calculator for your exact layout.
How much waste should I add for siding?
Plan 10% for a boxy home, 15% for moderate trim and gables, and up to 20% for homes with many corners and dormers.