Siding Calculator
Calculate siding for house: panel count, J-trim, outside corners, starter strip by facade area.
Total wall area to be clad, excluding windows and doors, in m²
Combined height of all outside corners (e.g. 4 corners × 3 m = 12 m)
Standard vinyl siding — about 0.85 m² per panel (check the manufacturer's pack)
Calculation formula
Panels = ⌈Facade area ÷ Panel area × 1.1⌉; J-trim ≈ house perimeter; Corners = total corner height
The 10% reserve covers cuts at corners, openings, and bypasses. J-trim runs along the top, bottom, and around all openings — approximated as the house perimeter.
About the siding calculator
The siding calculator quickly estimates the materials needed to clad a house: panel count, linear meters of J-trim, and outside corner posts. You only need the facade area (minus windows and doors) and the total height of all outside corners.
It works for vinyl, metal, fiber-cement, and foundation siding — only the useful area per panel changes, which is printed on the manufacturer's pack (Docke, Mitten, James Hardie, Cedral, etc.).
The calculator automatically adds a 10% reserve for cuts at corners and openings. All math runs in your browser with no data sent to a server — you get a clean order list for siding and trim.
Benefits
All trim at once
Panels, J-trim, and corner posts — a single calculation from facade area
Cut reserve included
Automatic 10% allowance — the typical cut reserve for siding around corners and openings
Any siding type
Vinyl, metal, fiber-cement, foundation — change the panel area and recalculate
Frequently asked questions
Vinyl or metal siding — which to choose?
Vinyl siding is 1.5–2× cheaper, lighter to install, and never needs repainting, but it can fade in the sun after 10–15 years. Metal siding costs more but holds its shape better on large walls and won't burn — usually the pick for cottages and buildings over two stories.
Why is panel consumption set to 0.85 m²?
0.85 m² is the standard useful area of a vinyl siding panel after locking together (typical panel ~3.66 × 0.23 m). Metal and fiber-cement panels are different sizes — take the figure from the manufacturer's pack and plug it into the calculator.
Do I need a furring/strapping layer under siding?
Yes — siding is always installed on furring strips: 50×50 mm wooden battens or galvanized metal profile spaced 30–40 cm apart. The strapping creates a ventilation gap and holds the insulation; without it, siding warps quickly and condensation builds up.
Why are thermal expansion gaps important?
Vinyl siding expands in heat and shrinks in cold — a 3-meter panel can move up to 1 cm. Each panel is nailed through the center of the slot with a 1 mm gap at the head, and 5–6 mm of clearance is left between panel ends and J-trim — otherwise the siding buckles into a wave.
How much J-trim should I order?
J-trim runs along the top and bottom of the cladding plus around every window and door. As a first approximation it equals the house perimeter plus 4–5 m for each opening. The calculator estimates the perimeter from facade area and corner height — round up to whole 3.8 m sticks.
Is a 10% cutting reserve enough?
For a rectangular house with no bay windows — yes. For complex facades (gables, dormers, many openings), use a 12–15% reserve. The calculator already rounds up to whole panels, which is enough for an average one- or two-story home.