Metal Roof Calculator
Enter the building size, pitch and the coverage width of your panel. You get the number of panels, the length of each and the total linear length. Results update as you type.
Metal roofing panels
30 panels
14 per slope × 2 slopes · 5% extra
30 panels, each cut to about 17 ft (5.18 m).
- Panels per slope14
- Length of each panel17 ft (5.18 m)
- Total linear length510.0 ft
- Roof area1,409 sq ft (130.9 m²)
- Area covered by panels1,409 sq ft (130.9 m²)
- At your price per panelAdd a price
Panels run from eave to ridge. Count and length come from your coverage width; order lengths with your supplier and add trim, closures and fasteners separately.
Planning estimate, not a quote. Disclaimer
How the metal roof calculator works
Metal panels run from the eave up to the ridge, side by side across the length of the roof. The count across is the roof length (with overhang) divided by the panel's coverage width, the width it covers once the ribs overlap, rounded up. Each panel is as long as the slope, rounded up to the next foot because panels are cut to length.
Panels per slope = (length + 2 × overhang) ÷ coverage, rounded up
Panels = panels per slope × slopes × (1 + extra %)
Example: the default 40 × 28 ft building with a 12-inch overhang and 6/12 pitch has a 16.8 ft slope length, so panels are about 17 ft long. A 36-inch coverage panel needs 14 per slope, 28 for the two slopes and 30 with 5% extra.
Coverage width changes the count
| Coverage width | Panels per slope | Total with 5% extra |
|---|---|---|
| 12 in | 42 | 89 |
| 16 in | 32 | 68 |
| 18 in | 28 | 59 |
| 24 in | 21 | 45 |
| 36 in | 14 | 30 |
Coverage width is not the sheet width. MBCI's PBR panel, for example, is listed with 36 inches of coverage and lengths from 5 to 50 feet, and Metal Sales' residential brochure shows standing-seam and ribbed profiles in coverage widths from 12 to 36 inches. Read the coverage on your product's data sheet.
Before you order
- Minimum slope depends on the panel. MBCI lists ½:12 for PBR; Metal Sales' residential exposed-fastener and standing-seam profiles list 3:12. Check your data sheet.
- Trim, ridge cap, closures, fasteners and underlayment are ordered separately. Use the underlayment calculator for rolls.
- Hip roofs and valleys need angled cuts and more waste than this gable or shed model.
Frequently asked questions
How many metal roofing panels do I need?
Divide the roof length by the panel coverage width and round up, then multiply by the number of slopes. The example roof needs 30 panels at 36-inch coverage.
What length should the panels be?
Eave to ridge along the slope, including the overhang. The example works out to 16.8 ft, so order 17-ft panels. Confirm the length with your supplier.
What is panel coverage width?
The width one panel covers after it overlaps its neighbor. It is smaller than the sheet width. 36 inches is common for ribbed panels, and Metal Sales’ residential brochure shows coverage widths from 12 to 36 inches.
How much extra metal roofing should I order?
The calculator adds 5% by default. Simple roofs may need less; roofs with hips, valleys or many penetrations need more.
What is the minimum slope for a metal roof?
It depends on the panel and the manufacturer, from ½:12 to 3:12 for the products cited on the methodology page. Follow your panel data sheet.
Related
Other roofing calculators
Sources
- MBCI: PBR panel (36 in coverage, minimum slope 1/2:12, lengths 5 to 50 ft) (checked Nov 12, 2026)
- Metal Sales: Residential metal roofing brochure (panel profiles and minimum slopes) (checked Nov 12, 2026)