Vinyl Siding Calculator
Get an accurate estimate for your vinyl siding project. Enter your wall dimensions, number of walls, windows and doors with their sizes. Choose the siding style (horizontal lap, vertical board and batten, shake/shingle, or insulated). The calculator deducts window and door areas, applies the appropriate waste factor, and gives you the exact number of squares of siding needed, plus estimated pieces, starter strip length, J-channel, and trim. Optional pricing per square gives you a material cost estimate.
Length of the wall (or house perimeter for total estimate)
Height from foundation to eaves
Number of walls with these dimensions (leave 1 for a single wall)
Total number of standard windows
Average window width (or 0 to skip deduction)
Average window height
Total number of exterior doors
Average door width (standard = 3 ft)
Average door height (standard = 7 ft)
Cost per 100 sq ft square (100 sq ft) of siding material
Gross Area = Length × Height × Sides
Deductions = (Windows × W × H) + (Doors × W × H)
Net Area = Gross − Deductions
Total with Waste = Net × (1 + Waste%)
Squares to Order = Ceil(Total ÷ 100)
Waste Factors:
Horizontal: 10% | Vertical: 12%
Shake: 15% | Insulated: 10%
1 Square = 100 sq ft
Standard window deduction: ~15 sq ft
Standard door deduction: ~21 sq ft
4 walls, 40′ long × 20′ tall (each side), 8 windows (3×4 ft), 2 doors (3×7 ft), horizontal style.
Gross: 40 × 20 × 4 = 3,200 sq ft
Windows: 8 × 12 = 96 sq ft
Doors: 2 × 21 = 42 sq ft
Net: 3,200 − 138 = 3,062 sq ft
With 10% waste: 3,062 × 1.10 = 3,368 sq ft
Squares needed: 3,368 ÷ 100 = 33.68 → 34 squares
At $100/square: $3,400 material cost
Starter strip: 160 ft | J-channel: ~550 ft
How is vinyl siding measured and sold?
Vinyl siding is sold by the "square" — a unit of 100 square feet. One square covers 100 sq ft of wall area. To calculate squares: Gross wall area = perimeter × height. Subtract windows and doors (15 sq ft per window, 21 sq ft per door). Divide by 100 and round up. Add 10-15% for waste (more for gables and complex roofs). Example: 40×10 ft wall = 400 sq ft, minus 8 windows (120 sq ft) and 2 doors (42 sq ft) = 238 sq ft net = 2.38 squares → order 3 squares with waste. Each square typically contains 20-24 pieces of siding.
How much does vinyl siding cost?
Vinyl siding cost varies by quality: Builder-grade: $2-4 per sq ft installed ($200-400 per square). Standard: $4-7 per sq ft ($400-700 per square). Premium: $7-11 per sq ft ($700-1,100 per square). Insulated: $5-9 per sq ft ($500-900 per square). Materials only: $0.60-2.00 per sq ft ($60-200 per square). Labor: $2-4 per sq ft. For a typical 2,000 sq ft home: $5,000-14,000 installed. Additional costs: old siding removal ($1-2/sq ft), sheathing repair ($500-1,000), trim ($2-4/linear ft), soffit and fascia ($3-6/linear ft).
What waste factor should I use for vinyl siding?
Recommended waste factors: Simple rectangular house with few cutouts: 5-10%. House with gables, dormers, and multiple cutouts: 10-15%. Complex architecture (multiple roof lines, bay windows): 15-20%. First-time installer: add 5%. Vertical siding: 10-15% waste (more cuts). Shake siding: 10-15% (pattern matching). Gable ends waste: approximately 15% of the gable area due to angled cuts. A good rule: order the calculated squares plus 1 extra square minimum for complex roofs. Most suppliers accept returns of unopened boxes within 30 days.
Can vinyl siding be installed over existing siding?
Yes, but with conditions. You CAN install over: Existing wood lap siding (if flat and sound), Existing vinyl (if not damaged), Existing fiber cement (if surface prepared). You CANNOT install over: Brick (need furring strips), Aluminum siding (too smooth — need texture), Damaged/rotted wood (must repair first). Requirements: Existing surface must be flat, clean, and structurally sound. Add furring strips if needed for flatness. Extend window and door jambs (new siding adds thickness). Check local building codes — some areas require removal of existing siding for moisture inspection. Installing over existing siding saves $1-2/sq ft in demolition costs.
🔗 Related Calculators
📐 Formula
Gross Area = Length × Height × Sides
Deductions = (Windows × W × H) + (Doors × W × H)
Net Area = Gross − Deductions
Total with Waste = Net × (1 + Waste%)
Squares to Order = Ceil(Total ÷ 100)
Waste Factors:
Horizontal: 10% | Vertical: 12%
Shake: 15% | Insulated: 10%
1 Square = 100 sq ft
Standard window deduction: ~15 sq ft
Standard door deduction: ~21 sq ft
📝 Example Calculation
4 walls, 40′ long × 20′ tall (each side), 8 windows (3×4 ft), 2 doors (3×7 ft), horizontal style.
Gross: 40 × 20 × 4 = 3,200 sq ft
Windows: 8 × 12 = 96 sq ft
Doors: 2 × 21 = 42 sq ft
Net: 3,200 − 138 = 3,062 sq ft
With 10% waste: 3,062 × 1.10 = 3,368 sq ft
Squares needed: 3,368 ÷ 100 = 33.68 → 34 squares
At $100/square: $3,400 material cost
Starter strip: 160 ft | J-channel: ~550 ft