How Many Squares of Siding Do I Need? House Size Chart
A square of siding covers 100 sq ft of wall. Add up the wall and gable area, take out large doors and windows, add 10% for cuts, and divide by 100. A 48 × 28 ft one-story ranch with 8 ft walls needs about 12.3 squares. The siding calculator does the math for your house, including gables.
How to measure a house for siding
- Walls: measure around the house at the foundation and multiply by the wall height (from the bottom of the siding to the eaves). On a two-story house, measure the full height.
- Gables: each triangular end is width × height ÷ 2, where height runs from the eaves line up to the peak. A hip roof has no gables.
- Openings: subtract garage doors and big windows. Many installers leave small windows in as their extra.
- Waste: add 10% for a simple house, 15% for lots of corners, dormers and gables.
squares = (walls + gables − openings) × 1.1 ÷ 100
Siding needed by house size
Rectangular houses with gables on the two short ends, a 6/12 roof pitch, typical door and window area taken out, and 10% extra. Floor area is approximate; your wall area depends on height and shape, so measure for a real order.
| House | Example | Wall + gable sq ft | Squares | Vinyl boxes |
|---|---|---|---|---|
| 24 × 20 ft, 8 ft walls | Small one-story or large garage | 804 | 7.2 | 4 |
| 36 × 26 ft, 8 ft walls | One-story, about 950 sq ft | 1,161 | 10.1 | 6 |
| 48 × 28 ft, 8 ft walls | One-story ranch, about 1,350 sq ft | 1,412 | 12.3 | 7 |
| 60 × 30 ft, 9 ft walls | One-story ranch, about 1,800 sq ft | 1,845 | 16.5 | 9 |
| 40 × 28 ft, 18 ft walls | Two-story, about 2,250 sq ft | 2,644 | 24.7 | 13 |
| 50 × 32 ft, 18 ft walls | Two-story, about 3,200 sq ft | 3,208 | 29.8 | 15 |
Lap plank coverage
Fiber cement and wood lap siding are sold by the plank, usually 12 ft long. Each plank covers its length times its exposure (the part that shows after the next plank overlaps it).
| Plank width | Exposure | Sq ft per 12 ft plank | Planks per square |
|---|---|---|---|
| 6.25 in | 5 in | 5.00 | 20 |
| 7.25 in | 6 in | 6.00 | 17 |
| 8.25 in | 7 in | 7.00 | 15 |
| 9.25 in | 8 in | 8.00 | 13 |
| 12 in | 10.75 in | 10.75 | 10 |
Trim and extras
- Corner posts: one for each inside and outside corner, the full wall height.
- J-channel: around every window and door and up the gable rakes.
- Starter strip: the full distance around the house.
- House wrap: about the same area as the siding.
- Soffit and fascia: measured by the length of the eaves; the roofing calculator helps if you're redoing the roof at the same time.