Siding Calculator: Squares & Panels Needed
Estimate how many squares (100 sq ft) and how many pieces of siding you need for a house or shed, minus openings and plus waste.
Siding is sold by the square, which is 100 sq ft of wall. A one-story house with a 160 ft perimeter, 9-ft walls, 200 sq ft of gables and 12 openings needs about 16 squares with 10% waste. Formula: (perimeter × height + gables − openings) × 1.10 ÷ 100.
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How to calculate siding
Siding is sold by the square — 100 square feet of wall coverage. To estimate it, find the gross wall area, subtract doors and windows, and add waste for cuts.
net area = gross − doors (21 sq ft) − windows (15 sq ft) − garage doors
squares = net area × (1 + waste %) ÷ 100
A gable end is a triangle: ½ × base × height. Add both ends. For multi-story houses, multiply perimeter by the total wall height, or calculate each story separately.
Siding squares by house size (one story, 9 ft walls, typical openings)
| House footprint | Perimeter | Net wall area | Squares (+10%) |
|---|---|---|---|
| 24 × 32 ft | 112 ft | 984 sq ft | 10.8 |
| 28 × 40 ft | 136 ft | 1228 sq ft | 13.5 |
| 30 × 50 ft | 160 ft | 1458 sq ft | 16.0 |
| 40 × 60 ft | 200 ft | 1888 sq ft | 20.8 |
The chart assumes a gable end roughly 7 ft tall at the peak; use your own gable area for accuracy.
Typical waste
Ten percent is normal for simple houses and 15% for houses with many corners, dormers or diagonal runs. Siding is manufactured in lots, so order everything together to avoid color differences.
Accessories
Siding projects also need trim around windows and doors, outside and inside corner posts, J-channel, starter strips, fasteners, flashing and housewrap. Count these by linear feet of edge. Before re-siding, check the walls for moisture and add insulation if you're opening them up — see the insulation calculator. For the roof above, use the roofing calculator.
Frequently asked questions
What is a square of siding?
A square is 100 square feet of wall coverage.
How do I measure a gable for siding?
Multiply the base of the gable by its height and divide by two. Add both gable ends.
How much siding waste should I allow?
Add about 10% for typical homes and up to 15% for complex rooflines or diagonal patterns.
How many pieces of vinyl siding are in a square?
A 12-foot double-4-inch panel covers about 8 square feet of wall, so roughly 12–13 panels per square. Check the box label.
How much siding do I need for a 2,000 sq ft house?
A two-story 2,000 sq ft house usually has about 2,000–2,400 sq ft of wall area before openings — roughly 20–25 squares with waste.
Vinyl, fiber cement or wood?
Vinyl is the cheapest and lowest maintenance; fiber cement is durable and fire-resistant but heavy and costlier; wood looks best but needs regular painting or staining.
Do I need housewrap under siding?
Yes. A weather-resistant barrier under siding sheds water that gets behind it and is required by most codes.
How do I price siding per square?
Installed siding is quoted per square. Multiply the squares from this calculator by the quoted price per square, then compare with material-only prices.
Sources and further reading
- Vinyl Siding Institute — VSI: vinyl siding installation resources
These references support the general guidance on this page. The calculator applies the standard formulas shown above to the numbers you enter.
Related calculators
. Estimates only. Always confirm quantities with your supplier or a qualified contractor before ordering, and add extra for waste and site conditions.