Metal Roof Panel Calculator
A metal roof panel length calculator and a metal roof panel calculator in one: use mode A to size panel length from the eave-to-ridge slope plus overhang, or mode B to count how many panels a roof width needs at your coverage width.
Coverage width is the width each panel covers after the overlap — corrugated is often 3 ft; 16-inch standing seam covers 1.33 ft.
Estimates only — not financial advice. This calculator gives approximate figures for planning. It is not financial, tax, or legal advice; check with a qualified professional before making decisions.
How the metal roof panel calculator works
Metal panels run from ridge to eave in one piece. Panel length is the slope distance you measure along the roof surface, plus the overhang past the eave converted to feet — that overhang is what throws water clear of the fascia.
Panel count is the roof width divided by each panel’s coverage width, rounded up, times the number of slopes. Coverage width is not the panel’s full width: it is what remains after the side overlap — a 36-inch corrugated panel typically covers 3 ft, while 16-inch standing seam covers 1.33 ft.
length = slope + overhang/12 · panels = ⌈width / coverage⌉ × slopes
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Metal roof panel calculator FAQ
How long should metal roof panels be?
Exactly the eave-to-ridge slope distance plus your overhang (usually 1–3 inches past the eave). Measure along the roof surface, not the horizontal run. Enter the numbers in mode A above.
What is panel coverage width?
The width each panel actually covers after the side lap — corrugated panels typically cover 3 ft, 5V-crimp about 2 ft, and 16-inch standing seam covers 1.33 ft. Use the manufacturer’s coverage figure, not the flat width.
Standing seam vs corrugated metal roof?
Corrugated/5V is cheaper and screws through the face; standing seam hides fasteners in raised seams, sheds water better on low pitches, and lasts 40–70 years, at roughly double the material cost.
How much overhang on a metal roof?
1–3 inches past the eave board is typical — enough to drip water clear of the fascia, short enough to stay stiff in wind. The default here is 2 inches.
How many metal roof panels do I need?
Divide the roof width by the panel coverage width and round up, then multiply by the number of slopes. A 30 ft wide, 2-slope roof with 3 ft coverage needs ⌈30/3⌉ × 2 = 20 panels — switch to mode B above.