Siding Calculator
Calculate siding in squares and boxes from your house dimensions — walls plus gables, with professional-style opening allowances, waste factor and cost estimate for vinyl or fiber cement.
Sum of all wall lengths
Per story; use total for two stories
Each gable: width × height ÷ 2
Garage doors + picture windows only
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Enter a price per square to estimate cost.
You might also need:Board and Batten Calculator·Roofing Calculator
Siding estimation math
squares = (area × waste) ÷ 100
A 140-foot-perimeter single story with 9-foot walls and one gable end: 1,260 + 120 − 130 = 1,250 sq ft, or 13.8 squares with 10% waste. That's 7 boxes of vinyl or about 229 fiber cement planks.
Coverage by siding type
| Siding | Unit | Coverage | Material $/square |
|---|---|---|---|
| Vinyl (D4/D5) | Box | 200 sq ft | $80–$250 |
| Fiber cement lap | Plank 8¼×144″ | ~6 sq ft @ 7″ exposure | $200–$350 |
| Engineered wood | Plank | ~6.5 sq ft | $150–$300 |
| Board & batten panels | 4×8 sheet | 32 sq ft | $150–$400 |
Don't forget the extras
- House wrap: one 9×100 ft roll covers ~900 sq ft of wall.
- Trim: J-channel around every opening, corner posts per corner, starter strip along the base — supplier will take your opening/corner counts.
- Board & batten style? Get exact board and batten counts from the board and batten calculator.
- Painting instead of replacing? The paint calculator handles exterior walls too.
Frequently asked questions
How is siding measured and sold?+
Like roofing, siding is quoted in squares of 100 square feet. Vinyl siding typically comes in boxes of 2 squares (200 sq ft); fiber cement planks are sold per piece, covering about 6 sq ft each for standard 8¼ × 144 inch boards at 7 inch exposure.
How many squares of siding does an average house need?+
A single-story 1,500 sq ft ranch typically needs 12–15 squares; a two-story colonial 20–25 squares. Wall area = perimeter × wall height, minus openings, plus gables — this calculator walks through exactly that.
Should I subtract windows and doors from siding?+
Subtract large openings (garage doors, picture windows) but leave standard windows and doors in the count — the J-channel, trim and cutting waste around each opening roughly cancels out its area. This is how professional estimators do it.
How much does siding cost?+
Vinyl siding materials run $80–$250 per square depending on grade; fiber cement $200–$350 per square. Installed, expect $300–$600 per square for vinyl and $500–$1,000+ for fiber cement including trim and house wrap.
How do I calculate gable area for siding?+
Each gable triangle is width × height ÷ 2. A 30-foot-wide gable rising 8 feet adds 120 sq ft. Enter the total of all gables in the gable field and the calculator adds it to your wall area.