How to Price Siding Per Square (With a Worked Example)
Updated October 18, 2026 · 6 min read
Siding is bought and priced by the square - 100 square feet of wall. Get the squares right and the rest of the estimate falls into place. Here's the method, start to finish, on a real-sized house.
Step 1: measure the walls
For each wall, multiply length by height (top of foundation to soffit). For gable ends, add the triangle: half the width times the rise. On a 6/12 roof the rise is half the half-width - a 28 ft gable rises 7 ft.
Step 2: subtract the openings
Subtract windows, doors and garage doors. A common shortcut: about 15 sq ft per average window and 20 sq ft per entry door; measure garage doors. Some contractors only subtract openings larger than 30 sq ft to build in a little extra - be consistent either way.
Step 3: add waste and convert to squares
Add 10% for a simple house, up to 15% for lots of corners, gables or bump-outs. Divide by 100 and round up - that's your squares.
Step 4: the trim and accessories
Siding without trim isn't a job. Take these off by the linear foot:
- Starter strip: the house perimeter.
- J-channel: around every window and door, plus along the soffit and gable rakes.
- Outside and inside corners: wall height x number of corners.
- House wrap: same area as the walls, bought by the roll.
Worked example: a 40 x 28 ft ranch
Walls: perimeter 136 ft x 9 ft = 1,224 sq ft. Two gables at 6/12: 1/2 x 28 x 7 = 98 sq ft each, 196 total. Gross = 1,420 sq ft.
Openings: 10 windows x 15 = 150, 2 doors x 20 = 40, one 16 x 7 garage door = 112. Total 302 sq ft. Net = 1,118 sq ft.
Plus 10% waste = 1,230 sq ft = 12.3, so order 13 squares.
| Line | Qty | Example price | Total |
|---|---|---|---|
| Vinyl siding (material) | 13 sq | $140 / sq | $1,820 |
| Install labor | 13 sq | $150 / sq | $1,950 |
| J-channel | 220 LF | $1.10 / LF | $242 |
| Outside corners | 4 x 9 ft | $30 each | $120 |
| Starter strip | 136 LF | $0.60 / LF | $82 |
Use your own numbers
The prices above are only examples to show the math. Use your supplier's prices and your crew's real production rate - and re-check them every season.
Draw the house in the Sentinel Nexus 3D Builder and the exterior takeoff counts squares, trim, wrap and labor for you - then sends the estimate.
Try it on your next houseFrequently asked questions
How much is a square of siding?
A square is 100 square feet of wall coverage. A box of vinyl siding usually covers about two squares - check the label.
Do I subtract windows when measuring siding?
Most contractors subtract windows and doors but keep the waste factor; cutting around openings creates scrap, so don't subtract too aggressively.
How much waste for siding?
Around 10% for simple shapes and up to 15% for complex houses with many corners, gables or dormers.