Quick answer: Siding is sold by the 'square' (100 sq ft). Multiply wall perimeter ร height, subtract doors and windows, divide by 100 for squares, and add 10% for waste.
This siding calculator estimates how much vinyl or fiber cement siding you need โ in squares and boxes โ after subtracting doors and windows, plus an estimated material cost with a waste factor.
Siding is estimated and sold by the square โ one square equals 100 square feet of wall coverage. Most vinyl siding is boxed so that one box (usually two cartons) covers about 200 sq ft, or 2 squares. Fiber cement lap siding is sold by the piece, but suppliers still quote coverage per box, so enter your product's box coverage above.
Siding has more waste than most materials because every piece is cut to length at corners, around windows, and along the roofline. A 10% waste factor is standard for straight walls; use 15% for homes with many gables, dormers, or angled cuts.
Multiply your total wall length (perimeter) by wall height, subtract door and window area, then divide by 100. A typical 1,500 sq ft single-story home needs roughly 15โ18 squares of siding after waste.
Most vinyl siding boxes cover about 200 square feet (2 squares), containing two cartons. Fiber cement coverage per box varies by exposure, so check your product's label and enter it above.
Add 10% for straight walls and up to 15% for homes with many gables, corners, or dormers, since each piece is cut to fit.
For each triangular gable, multiply the width by the height and divide by two, then add that area to your total wall area before calculating.
Vinyl siding materials commonly run $150 to $250 per square, while fiber cement runs higher. Enter your local price per square above for an exact material estimate.
At 10% waste and 200 sq ft coverage per box, the standard vinyl carton. One square is 100 sq ft. Openings not deducted.
| Perimeter | Wall height | Gross area | Squares @ 10% waste | Boxes (200 sq ft) |
|---|---|---|---|---|
| 100 ft | 8 ft | 800 sq ft | 8.8 sq | 5 |
| 120 ft | 8 ft | 960 sq ft | 10.6 sq | 6 |
| 140 ft | 9 ft | 1,260 sq ft | 13.9 sq | 7 |
| 160 ft | 9 ft | 1,440 sq ft | 15.8 sq | 8 |
| 180 ft | 10 ft | 1,800 sq ft | 19.8 sq | 10 |
| 200 ft | 10 ft | 2,000 sq ft | 22.0 sq | 11 |
| 240 ft | 12 ft | 2,880 sq ft | 31.7 sq | 16 |
| 280 ft | 12 ft | 3,360 sq ft | 37.0 sq | 19 |
Deduct only openings larger than about 30 sq ft โ a standard window generates enough offcut waste to cancel itself out. Fibre cement and engineered wood are usually sold by the piece rather than the square.
Every constant this calculator uses and where it comes from, so you can check it rather than take our word for it.
Local codes amend the model IRC and adopt different cycles — your building department governs. Manufacturers revise yields; where your product's data sheet disagrees with a default here, use the product's number. See our full methodology.