How Much Siding Do I Need for a House? (2026 Guide)
Measure each wall, subtract doors and windows, then add 10% for waste — see the step-by-step method and a chart for common home sizes.
Siding is sold in squares — not square feet
One square of siding = 100 sq ft of wall it covers — the unit suppliers quote. A roofing square is also 100 sq ft, but roofing is measured on the slope; siding counts flat wall area, so figure the net wall area — the coverage on the box is already net.
How to figure your siding, step by step
1. Measure every wall
For each exterior wall, multiply width × height, then add them up. A 60 ft wall at 8 ft high is 60 × 8 = 480 sq ft.
2. Subtract doors and windows
A standard exterior door is about 20–21 sq ft; a window about 12–15 sq ft. Using ~21 and ~15 is close enough — step 4 adds cushion.
3. Add up the net wall area
Gross wall area minus all openings = the net wall area your siding must cover.
4. Add 10% for waste
Cuts around corners and openings, starter strips and future repairs all eat siding. Multiply net area by 1.10.
5. Divide by 100 to get squares
Siding is ordered in squares, so divide your sq ft (including waste) by 100. Example: 1,826 ÷ 100 ≈ 18.3 squares.
6. Convert to boxes if you're buying vinyl
Vinyl usually comes boxed: 1 box ≈ 200 sq ft (2 squares), though coverage varies by brand — check the carton. So 1,826 sq ft ÷ 200 ≈ 9.1 → 9–10 boxes.
Worked example: a 1,500 sq ft single-story ranch
Say the exterior walls run about 230 linear ft at 8 ft high — typical with an attached garage and bump-outs counted:
Gross walls: 230 × 8 = 1,840 sq ft.
Doors and windows: ≈180 sq ft (3 doors, 7–8 windows).
Net wall area: 1,840 − 180 = 1,660 sq ft.
Add 10% waste: 1,660 × 1.10 ≈ 1,826 sq ft.
Squares: 1,826 ÷ 100 ≈ 18.3.
Vinyl boxes: 1,826 ÷ 200 ≈ 9.1 → 9–10 (estimate — confirm carton coverage).
Siding needed for common home sizes
| Home size | Net wall area (est.) | Siding needed (incl. 10% waste) | Vinyl boxes (est.) |
|---|---|---|---|
| 1,200 sq ft ranch | ~1,330 sq ft | ~15 squares | ~8 boxes |
| 1,500 sq ft ranch | ~1,660 sq ft | ~18 squares | ~9–10 boxes |
| 1,800 sq ft ranch | ~1,990 sq ft | ~22 squares | ~11 boxes |
| 2,400 sq ft ranch | ~2,660 sq ft | ~29 squares | ~15 boxes |
Estimating gross wall area from floor area is a shortcut, not a measurement: rows assume a ranch with an attached garage, net wall area about 1.1× floor area after openings, and 8 ft walls (9 ft walls add ~10%). For a firm order, measure every wall yourself or use the siding calculator.
Before you buy
- Keep the full 10% waste allowance — corners, windows and gable cuts add up.
- Vinyl sells by the box; fiber cement and engineered wood by the square or piece. Ask for coverage per box and order in squares.
- If your current siding is sound, painting is far cheaper — check how many sq ft a gallon of paint covers first.
- Re-siding is the best time to upgrade wall insulation — what R-value do I need explains the targets.
Final tip
Round up to the next full square, and keep a spare vinyl box — matching a color years later is nearly impossible.
FAQ
Do I count the gables separately?
Yes — a gable is a triangle: base × height ÷ 2, measured from the wall line to the peak. A 24 ft gable rising 6 ft adds 24 × 6 ÷ 2 = 72 sq ft. Add it to the total — angle cuts burn waste, so keep the 10%.
How much siding does one box of vinyl cover?
Most vinyl boxes cover about 200 sq ft (2 squares), but coverage varies by brand and profile — the exact figure is on the carton. In the example above, 18.3 squares ≈ 9–10 boxes.
Should I order siding in square feet or squares?
Order in squares — suppliers price siding per 100 sq ft square. Add waste, divide by 100 (1,826 ÷ 100 ≈ 18.3 squares), and round up to 19. To compare a sq ft quote, multiply your squares by 100.
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