How this metal roof calculator works
Metal is ordered as discrete panels, not square feet — so the count comes from the ridge and the cut length comes from the slope:
panel length = (width ÷ 2) × √(1 + (pitch/12)²) · eave to ridge, one piece
Worked example: metal panels for a 40 × 30 roof
At 4/12 each slope runs 15.8 ft — the cut length is 15′-9 3/4″. The 40 ft ridge needs 14 36-inch panels a side: 28 panels, 1,328 ft² of metal over 1,265 ft² of roof. With 5% waste that's about $4,184 at $3/ft², plus roughly 1,063 screws and 2 rolls of underlayment.
How much does a metal roof cost by size?
| Footprint | Panels | Cost |
|---|---|---|
| 30 × 24 ft | 20 | $2,391 |
| 40 × 30 ft | 28 | $4,184 |
| 50 × 30 ft | 34 | $5,080 |
| 60 × 36 ft | 40 | $7,172 |
| Profile | Coverage | $/ft² |
|---|---|---|
| Corrugated | 36″ | $1.50–3.50 |
| Ribbed / R-panel | 24–36″ | $2.50–5 |
| Standing seam | 16″ | $4–8 |
Metal roof FAQ
How many metal roofing panels do I need?
Ridge length ÷ panel coverage width, per side: the default 40 ft ridge in 36 in panels is 13.3 → 14 panels a side, 28 total, each cut 15′-9 3/4″ eave to ridge at 4/12 on a 30 ft wide roof. Change the profile and the count re-runs.
How much does a metal roof cost?
Material for the default 1,200 ft² footprint runs about $4,184 in panels at $3/ft² with waste. By profile in 2026: corrugated $1.50–3.50/ft², ribbed $2.50–5, standing seam $4–8 — and installed metal roofing typically quotes at $10–20 per square foot, most of it labor and trim.
How long should metal roof panels be?
One piece, eave to ridge — 15′-9 3/4″ for the default roof — because horizontal laps are where screw-down roofs leak. Suppliers cut to the inch; keep panels under about 40 ft for shipping and thermal movement.
What roof pitch does metal roofing need?
Most exposed-fastener panels want 3/12 or steeper; standing seam with mechanically seamed ribs goes as low as ½/12 by manufacturer spec. Below those numbers water sits on the laps — check the panel’s tested minimum, not the metal itself.
How many screws per square of metal roofing?
About 80 per square (100 ft²) for exposed-fastener panels on the common 24 in purlin/screw grid — roughly 1,063 for the default roof with waste. Buy the washered screws the panel maker specs; ordinary screws weep at the washer in a season.
Is a metal roof worth it over shingles?
Metal costs 2–3× shingle material but lasts 40–70 years against 15–25, sheds snow, and drops cooling bills under light colors. The break-even usually lands around the second shingle roof you didn’t buy.
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