Metal Roofing Calculator

Metal panels run in one piece from eave to ridge, so you order a count and a cut length, not squares. Enter one side of the roof and the panel coverage width.

Metal panel takeoff

Formulas

Panel length = run × pitch multiplier + eave overhang Panels per side = ⌈ eave length × 12 ÷ coverage width (in) ⌉ Linear feet = panels × panel length Screws ≈ roof area ÷ 100 × screws per square

Coverage width is the width each panel adds after it overlaps the one before, not the overall sheet width. A typical R-panel is about 38 to 39 inches wide but covers 36. The ⌈ ⌉ brackets mean round up: the last panel is ripped to fit.

Worked example

40 ft gable, 15 ft run each side, 4/12, R-panel. Panel length = 15 × 1.0541 + 2 in = 15.98 ft (15' 11-3/4"). Panels per side = 40 × 12 ÷ 36 = 13.3 → 14. Both sides: 28 panels, 447 linear ft. Area 1,278 sq ft × 80 per square ≈ 1,023 screws.

Common panel profiles

Metal roofing panel profiles (check the manufacturer data)
Profile	Coverage	Fasteners	Typical use
R-panel / PBR	36 in	Exposed screws	Barns, shops, budget homes
Corrugated (2.5 in)	≈24–26 in (varies)	Exposed screws	Outbuildings, rustic homes
5V crimp	≈24 in	Exposed screws	Coastal and traditional homes
Snap-lock standing seam	12–18 in	Hidden clips	Homes; usually 3/12 and steeper
Mechanically seamed standing seam	12–24 in	Hidden clips	Low slopes (as low as 1/4/12) and commercial

Trim and accessories

Eave trim / drip edge: eave length on every side.
Rake (gable) trim: panel length × 2 per gable end.
Ridge cap: ridge length, plus closure strips (inside and outside) to match the panel profile.
Trim pieces usually come in 10 or 10.5 ft lengths; allow a few inches of overlap at each joint.

Panel cut lists are usually rounded to the inch. If your eave is not square to the ridge, measure each end of the roof and order to the longer one. Panels longer than about 20 ft need extra hands and care to avoid kinking.

Frequently asked questions

How do I calculate how many metal roofing panels I need?

Divide the eave length in inches by the panel coverage width and round up, for each side of the roof. A 40 ft eave with 36 inch coverage needs 14 panels per side.

How long should metal roof panels be?

The sloped distance from eave to ridge plus the overhang at the eave: horizontal run times the pitch multiplier, plus 1 to 2 inches of overhang (or what the manufacturer specifies).

How many screws per square for a metal roof?

Around 70 to 80 per 100 sq ft is a common rule of thumb for exposed-fastener panels. The manufacturer's fastening pattern governs, and high-wind zones need more.

Can metal roofing go on a low-pitch roof?

Exposed-fastener panels usually need about 3/12. Mechanically seamed standing-seam panels can go as low as 1/4/12 under the IRC.

Last reviewed 2026-10-10. Results are estimates for planning; confirm quantities with your supplier and requirements with your local building code and the manufacturer's instructions.