Siding Calculator
Estimate siding squares and boxes for a house or wall - with openings deducted, gables, and cost.
Add up all wall lengths around the house (the perimeter).
Foundation to eave. For split levels or varied heights, calculate each section separately.
Deducts 21 ft² each (3 × 7 ft). Include garage doors as ~3 windows each.
Deducts 15 ft² each (3 × 5 ft).
Total of all gable triangles: 0.5 × width × height each. Leave blank if none.
Your Siding Estimate
- Add up your wall length - walk the house perimeter and total all wall lengths.
- Enter the wall height - from foundation to eave; do split levels in sections.
- Count doors and windows - each opening is subtracted from the wall area.
- Add gable area if any - under Advanced - total the triangle areas above the eaves.
- Order the boxes shown - rounded up to whole boxes, all from one color lot.
Vinyl siding is ordered by the square (100 square feet), two squares to a box. A 1,500 square foot ranch typically needs 12 to 15 squares - 6 to 8 boxes - after subtracting doors and windows and adding 10 percent waste. Each gable end adds its width times height divided by two. Enter your wall length, height, and any gable area above for squares and boxes.
Walls Plus Gables, Minus Openings
How Much Siding Do I Need?
Siding is sold by the square - one square covers 100 square feet. Measure each wall (length times height), add up the areas, subtract the doors and windows, add a waste factor for cuts and corners, then divide by 100. This calculator does all of that and also converts squares into boxes, since vinyl typically comes packaged two squares per box and you order in whole boxes.
Deducting openings matters more on siding than people expect: a house with several large windows, a picture window, or a garage door can have a few hundred square feet of openings, which is real money in siding. Rather than hiding that in a big waste number, this calculator subtracts the openings directly and applies a realistic waste factor on top.
Waste Factor by House Complexity
Cuts, overlaps, corners, and the occasional cracked panel all add up - order extra accordingly:
| House type | Waste | Why |
|---|---|---|
| Simple rectangle | 10% | Few corners, straightforward runs |
| Standard house | 12% | Normal mix of windows and corners |
| Cut-up / dormers / angles | 15%+ | Many openings, gables, and short runs |
Quick Reference: Squares by Wall Area
| Net wall area | Squares (raw) | With 12% waste | Vinyl boxes |
|---|---|---|---|
| 500 ft² | 5 | 5.6 | 3 |
| 1,000 ft² | 10 | 11.2 | 6 |
| 1,500 ft² | 15 | 16.8 | 9 |
| 2,000 ft² | 20 | 22.4 | 12 |
Net area is after subtracting openings. Vinyl boxes at 2 squares each, rounded up.
Siding Cost by Material
Installed cost per square foot, US 2026:
| Material | Installed per ft² | Lifespan |
|---|---|---|
| Vinyl | $3–8 | 20–40 yrs |
| Engineered wood | $4–9 | 20–30 yrs |
| Fiber cement | $6–13 | 30–50 yrs |
| Wood | $5–12 | 20–40 yrs (needs paint/stain) |
Siding Formulas
Net area first, then squares, then boxes:
Net area = gross − openings (21 ft²/door, 15 ft²/window)
Squares = net × (1 + waste) ÷ 100
Boxes = squares ÷ squares-per-box (2 for vinyl), rounded up
For a gable, area = 0.5 × width × height. Add all gable triangles together and enter the total under Advanced.
The Trim Pieces This Calculator Does Not Count
Field siding is only part of the order. A vinyl job also needs a run of trim and accessory pieces that most quick calculators skip, and forgetting them stalls the install. Starter strip runs along the entire base of every wall - measure the total bottom perimeter in linear feet. J-channel wraps every window and door and runs along the roof rakes - measure the perimeter of each opening plus the rake lengths. Utility trim locks in the top course and the pieces under windows.
Corner posts run the full height of every outside and inside corner - count the corners and multiply by wall height. Order about 10 percent extra on the long accessory runs for cuts and overlaps. Undersill trim, drip cap, and a matching soffit and fascia package round out a typical order; price those separately from the field squares this tool gives you.
Install Note
- Vinyl siding is hung loose so it can expand and contract with temperature: nails are driven snug rather than tight and centered in the slots, and panels are not caulked at the ends. Pinning that movement is the most common cause of buckling and wavy walls, and it is spelled out in the industry installation practice.ASTM D4756 - Installation of Rigid PVC Siding and Soffit
Next Steps
Squares counted, plan the rest of the exterior:
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Frequently Asked Questions
What is a square of siding?
A square is the siding industry unit for 100 square feet of coverage. Vinyl is almost always sold by the square, usually packaged two squares to a box. To find squares, divide your net wall area (after waste) by 100; this calculator then rounds up to whole boxes for ordering.
How many squares of siding for a 1,500 sq ft house?
Wall area is not the same as floor area. A single-story 1,500 square foot ranch typically has about 14 to 18 squares of wall to side, while a two-story home of the same floor area needs more like 20 to 24 because there is more vertical surface. Measure the actual walls for an accurate number.
Should I subtract windows and doors?
Yes. This calculator subtracts 21 square feet per door and 15 square feet per window, plus you can deduct garage doors by counting them as about three windows each. On a house with large or numerous openings this is a meaningful reduction, so deducting them keeps you from over-ordering.
How do I handle gable ends?
A gable is a triangle, so its area is one-half the width times the height. Add up all your gable triangles and enter the total in the gable field under Advanced. The calculator includes it in the gross area before deducting openings and applying waste.
How much waste should I add for siding?
Use about 10% for a simple rectangular house, 12% for a standard home, and 15% or more for houses with many corners, dormers, angles, or windows, since each adds cuts and offcuts. Buy one or two extra boxes from the same color lot for future repairs regardless of the waste figure.