Siding Square Calculator â How Many Squares of Siding Do I Need?
Enter perimeter, wall height and openings to get squares of siding. No sign-up, no data stored.
Siding needed
How siding is calculated
- Wall area = perimeter à wall height â openings (doors and windows).
- Squares = wall area ÷ 100, the unit siding is sold in.
- Waste: add 10% for a simple rectangle, 15â20% for gables, corners and dormers.
- Gables: measure each gable as (base à height ÷ 2) and add it to the wall area.
For a two-story house, measure each floor's perimeter separately or multiply by the full height if the walls run straight through. Vinyl and fiber cement come in fixed-length panels, so corner and window cuts create real waste â round up to the next full square and buy one extra square for repairs.
House size â siding reference
Approximate squares for typical one-story homes (8-ft walls, 10% waste).
| House (ft) | Perimeter | Wall area | Squares |
|---|---|---|---|
| 24Ã36 | 120 ft | ~760 sq ft | 9 |
| 30Ã40 | 140 ft | ~920 sq ft | 11 |
| 32Ã48 | 160 ft | ~1,080 sq ft | 13 |
| 40Ã60 | 200 ft | ~1,400 sq ft | 16 |
Last updated: October 2026 · Assumes one story, 8-ft walls, ~200 sq ft of openings and 10% waste. Add gable areas for homes with peaked ends.
Siding FAQ
About 22â25 squares for a single-story 2,000-sq-ft house including gables and waste. Squares measure wall area, not floor area â use perimeter à height, subtract openings, add 10â15%.
One square is 100 square feet of coverage â the standard unit siding is sold and priced in. A 12-sq order covers 1,200 sq ft of wall.
10% for a simple rectangle, 15â20% for gables, dormers, corners and custom cuts. Fixed-length panels mean corner and window cuts always leave scraps.
Multiply the exterior perimeter by the wall height, subtract doors and windows (about 15â20 sq ft each), add gable areas, then apply the waste factor. Measure at the foundation line.
Yes, both are sold by the square (100 sq ft), so the quantity math is identical. Fiber cement costs 2â3Ã vinyl but lasts decades longer; vinyl is cheaper, lighter and faster to install.
Related calculators & guides
How Much Siding Do I Need?
Estimate siding in squares: the exterior wall area formula, subtracting doors and windows, coverage by lap exposure, and a worked example for a 1,200 sq ft house.
Read the guide →