Metal Roofing Panel Calculator — m to panels, screws, cost
How to use this calculator
Enter your footprint length × width plus the pitch angle (or a measured roof area in m²), pick the panel profile and length, and the output gives the exact panel count, ridge cap pieces, eave/rake trim and screw boxes you take to the supplier. The 1/cos θ pitch factor scales the plan area to the true slope — an 8×10 m footprint at 26° yields 89 m², not 80.
Panel types — Standing seam 400–475 mm, Corrugated 660 mm, R-Panel 914 mm coverage width.
Pitch — Entered as degrees. The calculator applies the pitch factor (1/cos θ) to convert footprint to actual roof area.
Cost — Select your currency and enter price per panel for a full material estimate.
Saved Calculations
| Time | Type | Area m² | Panels | Ridge | Trim | Screws | Total |
|---|
How to Calculate Metal Roofing Panels (Metric)
Coverage width sets the panel count, so choose the profile first: standing seam covers 400 mm or 475 mm net after interlocking, trapezoidal corrugated covers 660 mm, and R-panel/PBR covers 914 mm after the side rib is nested. Enter the roof as a measured surface area, or as plan length × width with the roof pitch in degrees — in plan mode the factor 1/cos θ scales the footprint up to the true slope area. Match panel length to the full eave-to-ridge run where possible to avoid endlaps; only add an endlap row when the run is longer than the panels you can source.
The 10% default waste suits a simple two-sided gable. Drop to 5% for a clean rectangular monopitch and raise to 15% for hipped roofs or anything with valleys, dormers, or rooflights. Screws are estimated at ~8 per m² (≈80 per 10 m²): exposed-fastener sheets are fixed at every trough on eave and ridge and every second trough in the field, while standing seam uses concealed clips so the figure is a safe upper bound.
How to use
Use the L × W + Pitch tab for a footprint or Direct Area when you already have a measured surface from the roof area and pitch calculator. Select the profile, panel length and endlap, then open the cost panel and pick your currency for a material total. Compare against tiles with the shingle calculator and size low-slope areas with the flat roof membrane calculator.
Formulas
Pitch factor = 1 / cos(angle°). Actual roof area = footprint L × W × pitch factor × sides. Panels across = ⌈width ÷ panel coverage⌉. Rows lengthwise = ⌈slope length ÷ (panel length − endlap)⌉. Ridge cap = ⌈ridge ÷ 1.9 m⌉ (2 m pieces, 100 mm lap). Trim = (2 × eave + 2 × rake) ÷ 2 m. Screws ≈ 8 per m², then × waste factor.
FAQ
What coverage width should I use? Standing seam 400–475 mm after interlocking, corrugated 660 mm after side lap, R-panel 914 mm — always confirm the exact cover with your panel supplier.
What endlap for low pitch? For slopes below 15°, use 200–250 mm endlap with sealant tape. Standard pitch uses 150 mm.
What else should I budget? Closures, butyl tape, flashings and gutters — size rainwater goods with the gutter and downspout calculator and any timber framing with the lumber volume calculator or deck framing calculator for a porch addition.
On install day
European metal roofing in 2025 runs roughly €25–45/m² installed for 0.5 mm coated trapezoidal sheet and €60–90/m² for 0.5 mm standing seam — sheet only is about half that. The single most-forgotten line item is trim and flashings: eave drip, verge/gable trim, valley sheet, pipe collars and ridge filler add 15–25% to a sheet-only takeoff, so order them with the panels. EN 14782 covers self-supporting metal sheet; below 14° pitch use sealed laps and a fully supported underlay per BS 5534 / DIN 18299. Square the first sheet to the eave — 5 mm run-out across an 8 m run grows to 25 mm at the gable.
