How to use the metal roof calculator
- Measure the house. Enter the length along the ridge and the width from eave wall to eave wall.
- Add the overhang. The calculator adds it at the eaves (panel length) and at the gable ends (number of panels).
- Choose the pitch. Most metal panels need at least 3/12. Standing seam can go lower; check the maker's minimum.
- Choose the panel coverage. Use the coverage width, not the full sheet width. Common ribbed panels cover 36 in; standing seam panels usually cover 12 to 18 in.
Metal roof formulas
Panels per side = (house length + 2 × overhang) × 12 ÷ coverage width
Roof area = 2 × side length × panel length
Screws = roof area ÷ 100 × 80
The pitch multiplier is √(1 + (pitch ÷ 12)²). Round panels up to whole panels; the last panel on each side is usually trimmed lengthwise.
Worked example
A 50 × 30 ft house with 12 in overhangs and a 6/12 pitch: each side is 52 ft long and the run from ridge to edge is 16 ft. With the 1.118 multiplier, each panel is 17 ft 11 in long. With 36 in coverage you need 52 × 12 ÷ 36 = 17.3, so 18 panels per side and 36 panels in all. The roof area is 1,860 sq ft, which takes about 1,489 screws, 6 pieces of ridge cap, 104 ft of eave trim and 71.6 ft of rake trim.
Metal roofing panel types
| Panel | Coverage | Fasteners | Typical installed price |
|---|---|---|---|
| Corrugated / ribbed (R-panel) | 36 in | Exposed screws | $6 - $10 per sq ft |
| Standing seam (snap-lock) | 12 - 18 in | Hidden clips | $10 - $16 per sq ft |
| Metal shingles | Varies | Hidden | $9 - $15 per sq ft |
Compare the full price of a new roof by material with the roof replacement cost calculator. For asphalt shingles, use the roofing calculator.
Tips for ordering
- Order panels cut to the exact length so you avoid end laps, which can leak on low slopes.
- Buy matching closure strips for the eaves and ridge, butyl tape and touch-up paint.
- Exposed fastener panels use about 70 to 80 screws per square. Standing seam uses clips instead, usually every 1 to 2 ft along each seam.
- Check whether your roof deck needs new underlayment; synthetic or high-temperature underlayment is common under metal.
Frequently asked questions
How many metal roofing panels do I need?
Divide the length of each roof side (including overhangs) in inches by the panel coverage width and round up. A 52 ft side with 36 in panels needs 18 panels, so a two-sided gable roof needs 36.
How long should metal roof panels be?
Each panel runs from the eave to the ridge. Multiply half the house width plus the overhang by the pitch multiplier. A 30 ft wide house with 12 in eaves and a 6/12 pitch needs panels about 17 ft 11 in long.
How many screws per square for a metal roof?
Exposed fastener panels typically need about 70 to 80 screws per 100 sq ft, placed on the purlins or every 2 ft along the panel. Follow the maker's fastening pattern for your wind zone.
Is a metal roof cheaper than shingles?
No, a metal roof usually costs 1.5 to 3 times as much to install as asphalt shingles, but it lasts 40 to 70 years, about twice as long or more.
What is the coverage width of a metal roofing panel?
Most ribbed and corrugated panels cover 36 in after overlap. Standing seam panels usually cover 12, 16 or 18 in.
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Last updated October 2026.