Metal panel net coverage vs overall sheet width — the number that sets panel count
Every profile loses width at the lap or seam, so order by NET coverage, not the overall sheet width. Panels per plane = ⌈eave width ÷ net coverage⌉ — and coverage varies by brand even at the same nominal size.
What this diagram shows
Four metal roofing profiles in end-view cross-section, each dimensioned twice: the overall sheet or coil width in gray and the NET exposed coverage width in blue. A 7/8-inch corrugated sheet is about 39 inches overall but nets roughly 34-2/3 inches (32 to 37-3/8 by gauge and brand) after the side lap. R-panel/PBR is 38 inches overall and nets a true 36 inches because the purlin-bearing leg fully overlaps the next panel. A 5-rib ag/Tuff-Rib panel is sold by its 36-inch coverage, with the lap rib as extra width. A snap-lock standing-seam panel is about 22-1/8 inches of coil but nets 16 inches because roughly 6-1/8 inches is consumed forming the seam. Panels per plane equal the eave width divided by NET coverage width, rounded up — never the overall sheet width.
Metal Roofing Calculator
Free metal roofing calculator: panel count from NET coverage width, exposed-fastener screws or standing-seam clips, trim BOM, and underlayment. No signup.
