Metal Roofing Calculator — panels, squares and screws
Panels by count and length for a gable roof, from the footprint, the pitch and the panel's cover width, with squares, screws at a stated rate and the trim runs.
Panels by the count and the length for a gable roof, from the footprint, the pitch and the panel’s cover width — with the squares, the screws at a stated rate, and the trim runs.
| Panel length, each slope | — |
|---|---|
| Eave length | — |
| Panels | — |
| Roof area | — |
| Panel linear feet, with waste | — |
| Screws | — |
| Trim | — |
Metal roofing is bought by the panel, and a panel is a cover width times a length. A ribbed panel covers 36 inches of eave once the laps are taken; one maker’s 5V crimp covers 24 and its ⅞-inch corrugated 32; standing-seam pans come 12, 16 and 18 inches wide. Those are the widths this page offers, and they are the profiles of the makers cited below. Another maker’s panel of the same name can cover something else, which is what the ‘Other’ field is for. The eave length divided by the cover width, rounded up, is the panels per slope. The panel length is the slope run, half the width plus the overhang, times the pitch factor. It is cut to that length at the factory, so order it to the inch rather than in stock lengths. A 40 × 28 gable at 4:12 with a foot of overhang is 14 panels of 15’-10” a side in the 36-inch profile, 21 a side in 5V.
Squares are for the screws and the underlayment, not for the panels. The roof area in hundred-square-foot squares drives the fastener count, about 80 screws to the square. That is the rate one manufacturer publishes for a 36-inch exposed-fastener panel on screw lines 24 inches apart. It is an estimating rate, not a fastening schedule, and it counts panel screws only: the lap screws that stitch the sidelaps and the one per foot of trim and flashing are on top of it, which on a plain gable is roughly another third. The field is editable because your panel’s schedule and your wind zone replace the rate outright. Standing seam has no exposed screws at all, so the page prints none. The roofing-squares page carries the underlayment.
Five percent waste, not fifteen. Shingles lose a bundle to every hip and valley; a metal panel is cut once, to length, and the offcut from a hip on one side is often the piece for the other. Five percent covers the mis-cut and the damaged sheet on a plain gable. A hip roof or a roof with valleys wants more, and it wants the trapezoidal panels laid out on paper first. This page does not do that layout. It covers a plain gable, two slopes.
Pitch factor = √(rise² + 144) ÷ 12. Run = (width ÷ 2 + overhang) × factor; eave = length + 2 × overhang; panels per slope = ceil(eave × 12 ÷ cover width); area = 2 × eave × run; screws = ceil(squares × rate). Cover widths are each one manufacturer’s published product: 5V 24" and corrugated ⅞" 32" (McElroy Metal, 5V and Multi-Cor panel data), 5-rib 36" (Metal Roofing Source, Premium 5 Rib), standing seam 12/16/18" (McElroy Medallion-Lok). 80 panel screws per square on 24" screw lines is Western States Metal Roofing’s published estimating rate for a 36" exposed-fastener panel. It is a starting figure, not a schedule, and it excludes lap and trim screws. Trim: ridge = eave length; eave trim = 2 × eave; rake = 4 × run; closures = 3 × eave (two eaves and the ridge).
Worked example
A 40 × 28 ft gable at 4:12 with 12-inch overhangs, in 36-inch ribbed panels: how many panels, and how long?
- Pitch factor √(4² + 144) ÷ 12 = 1.0541.
- Run = (14 + 1) × 1.0541 = 15.81 ft, the panel length; eave = 40 + 2 = 42 ft.
- 42 × 12 ÷ 36 = 14 panels a side, 28 in all; area 2 × 42 × 15.81 = 1,328 ft² = 13.28 squares; at 80 screws a square, 1,063.
28 panels cut to 15'-10", about 465 linear feet with 5% waste, and a thousand screws. In 5V at 24 inches it would be 42 panels.
16 values on this page were driven in a browser and compared with independently derived figures on 2026-09-06 (661 values across 69 calculators site-wide).
Questions
How many metal roofing panels do I need?
Eave length ÷ the panel's cover width, rounded up, per slope. A 36" ribbed panel on a 42 ft eave is 14 panels a side; 5V at 24" is 21. The panel length is the slope run times the pitch factor, cut to length.
How many screws per square of metal roofing?
About 80 per 100 ft² for exposed-fastener panels on 24" screw lines — a manufacturer's published starting rate; the panel's fastening schedule and wind zone govern. Standing seam uses hidden clips, not screws.