Vinyl Siding Calculator
Vinyl siding panels, trim and accessories for a wall area.
Result appears here
Fill in the fields and press Calculate.
Formula, calculation, assumptions and sources
Squares = (perimeter × height + gables − openings) ÷ 100
Boxes (exact) = net area ÷ coverage per box; Boxes (recommended) = ⌈ net area × (1 + waste) ÷ coverage per box ⌉
Starter strip = wall perimeter; J-channel = total opening trim length
Corner posts = corners × (wall height ÷ 10 ft piece)
Run the calculation to see each step with your own numbers.
150 ft perimeter, 9 ft walls, 180 ft² gables, 120 ft² openings, 4 outside corners, 90 ft of opening trim, 200 ft²/box, 10% waste.
Net area = 1,410 ft² = 14.1 squares
Boxes = 1,410 ÷ 200 = 7.05 exact → ⌈1,551 ÷ 200⌉ = 8 recommended (10% waste)
Starter = 150 ft; J-channel ≈ 90 ft + rakes; corner posts = 4 (wall < 10 ft)
- J-channel length is what you enter for opening trim; add gable-rake length to it if you're not using an F-channel there.
- Corner-post count is pieces at wall height — if the wall is taller than one 10 ft post you'll splice, which this reflects.
- Soffit, fascia, F-channel, undersill/utility trim, house wrap and fasteners are separate.
- Coverage per box varies by profile and brand — a double-4 box is often ~200 ft², a double-5 slightly less.
- How many boxes of vinyl siding for an average house?
- A typical 1,500 ft² of wall is about 15 squares, or roughly 8 boxes at 200 ft²/box, before accessories. Add 10% for waste and always buy the accessory trim (starter, J-channel, corners) as separate line items.
- What accessories do I need besides the panels?
- Starter strip along the full base of every wall, J-channel around every window and door and up the gable rakes, a corner post at each outside and inside corner, and undersill/utility trim at the tops of walls. The calculator sizes the first three.
- How much coverage is in a box?
- Usually two squares — about 200 ft² — for a double-4 profile, a bit less for a double-5. Check the carton and enter the real figure so the box count is right.
Method & squares
Vinyl Siding Institute installation manual; a siding "square" = 100 ft² (1 roofing square = 100 ft² of roof surface. Universal roofing-trade convention (NRCA).).
About the Vinyl Siding Calculator
The Vinyl Siding Calculator gives siding squares and boxes plus a take-off of the accessory pieces that are easy to under-order — starter strip, J-channel, and outside and inside corner posts. Enter the wall perimeter and height, gable area, openings, corner counts and the total trim length around openings. Soffit, fascia, F-channel and utility trim are separate line items.
What you enter
- Wall perimeter
- Wall height
- Gable area
- Openings to deduct
- Outside corners
- Inside corners
- Total perimeter of all windows + doors — For J-channel: add up the trim length around every opening.
- Coverage per box (ft²) — Two 'squares' per box is common (200 ft²); check the carton.
- Waste allowance — Default 10%. Adjust to your own allowance — the exact figure is always shown too.
What you get back
- Siding squares — shown as the exact figure and, separately, a recommended figure with your waste allowance added.
- Boxes of siding — Exact = whole boxes for the net area. Recommended = whole boxes including the waste allowance.
- Starter strip — = wall perimeter. Sold in ~10 ft or 12 ft 6 in lengths.
- J-channel — Around every opening, plus gable rakes. Sold in ~12 ft 6 in lengths.
- Corner posts — One per corner, cut from ~10 ft lengths — this is the count of pieces at wall height.
The formula, a worked example, the assumptions behind it and the sources are shown in full below the calculator.
Related calculators
- Siding Calculator — Siding material and squares for the exterior walls of a building.
- Wall Square Footage Calculator — Wall area for one or more walls, with openings deducted.
- Roof Pitch Calculator — Roof angle, slope factor and rise-in-12 pitch from a rise and run.
- Roof Area Calculator — Sloped surface area of a simple gable or hip roof from its footprint and pitch.
Part of the Siding calculators.