Vinyl Siding Calculator — Squares, Panels & Trim
Calculate how much vinyl siding you need: total coverage in m² or squares, panel count from your profile's exposure width, and the trim that goes with it. Enter wall dimensions, subtract openings, and get the list with waste included.
Exterior wall build-up
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Save results to a project: budget and shopping list build themselves, and the whole plan exports as a PDF. Draw your floor plan and room sizes pre-fill the calculators.
How the vinyl siding estimate works
- 1Wall area = sum of all wall faces, minus windows and doors
- 2Convert to squares if ordering US-style: 1 square = 100 sq ft (9.29 m²)
- 3Courses = wall height ÷ panel exposure (a "double 4" panel exposes 8 in / 203 mm)
- 4Running length = courses × wall width; panels = running length ÷ panel length
- 5Apply 10% waste for cuts and laps — more on gables
- 6Trim is separate: starter strip (base perimeter), J-channel (around openings and eaves), corner posts
Worked example
Wall: 10 m wide, 2.5 m high, with 3 m² of window/door openings. Double-4 profile (203 mm exposure).
Net area 22 m² (≈ 2.4 squares) — order 2.5–3 squares with waste. That's 13 courses; plus 10 m starter strip, J-channel around openings, and 2 corner posts per corner.
Frequently asked questions
How many squares of vinyl siding do I need?
Total net wall area ÷ 9.29 m² (100 sq ft) per square, plus 10% waste. A typical single-storey house runs 12–18 squares. Boxes usually hold 2 squares — check the carton.
What is a "double 4" or "double 5" siding profile?
One panel moulded to look like two courses of 4-inch or 5-inch lap boards. A double-4 panel covers 8 inches (203 mm) of height, double-5 covers 10 inches (254 mm) — that exposure number drives the whole calculation.
What trim pieces does vinyl siding need?
Starter strip along the base, J-channel around every window, door and roofline, corner posts at every corner, and utility trim under windows. Trim is bought per running metre/foot — measure the perimeters, not the area.
How much waste should I allow for vinyl siding?
10% on plain rectangular walls; 15% with gables, since every gable course ends in an angled cut. Panels from different production runs can vary slightly in colour, so order the full job at once.
Do I need underlayment behind vinyl siding?
A weather-resistant barrier (house wrap) is required behind vinyl siding in most codes — the siding itself is not watertight, it's a rain screen. Add foam backer board if you want a flatter wall and some insulation value.