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RoofingVerified Formulas

Metal Roof Calculator

Estimate metal panel counts, linear footage, fasteners, and trim accessories.

Metal Roof Calculator Interactive Tool

Interactive Calculator

Enter your project dimensions below. Results update instantly.

Continuous run from eave to peak
typical value, change to match your product36 in for corrugated; 16-24 in for standing seam
typical value, change to match your productPanel cut allowance
Panel unit cost

Results

Panels to Order

31

Each panel cut to 18 ft
Total Linear Feet

558 lin ft

Total ordering footage
Fasteners (Screws)

~2,880

Neoprene-washer screws
Underlayment

2 rolls

High-temp synthetic rolls
Estimated Panel Material Cost:$2,511.00

Metal Roofing Panel Layout Formula

Panels per Slope = ⌈Ridge Length ÷ Panel Effective Width⌉ | Total Panels = Panels per Slope × Slopes × (1 + Waste % ÷ 100) | Fasteners ≈ Surface Sq Ft × 2

Formula Variables:

  • Panel Width:Coverage width of the profile after lap ribs are locked (commonly 36" for corrugated/R-panel, 16"–24" for standing seam).
  • Slope Length:Rafter length from eave to ridge.

Metal roof panels are ordered by custom cut-to-length linear dimensions corresponding to the slope length plus eave overhang.

Step-by-Step Worked Example

Example: 40-foot ridge gable roof with 18-foot slope using 36-inch R-panels

Installing 36-inch coverage corrugated metal panels on a two-sided gable roof with 40-foot eave length and 18-foot slope rafter length.

Ridge Length:40 ft
Slope Length:18 ft
Panel Width:36 in (3 ft)
Type:Gable (2 slopes)
Waste:10%
  1. Calculate panels per side: 40 ft ÷ 3 ft = 13.33 → 14 panels.
  2. Calculate total base panels for both sides: 14 × 2 = 28 panels.
  3. Add 10% cut waste allowance: 28 × 1.10 = 30.8 → 31 panels of 18 ft length.
  4. Calculate total linear footage: 31 panels × 18 ft = 558 linear feet.
  5. Calculate roof surface area: 40 ft × 18 ft × 2 = 1,440 sq ft.
  6. Fastener estimate: 1,440 sq ft × 2 screws/sq ft = 2,880 neoprene-gasketed roofing screws.
Order 31 custom-cut 18-ft panels (558 linear ft), 40 ft of ridge cap, and ~2,880 screws.

Input Explanations & Measurement Guidelines

Ridge / Eave Length

Typical: 30 to 50 ft

Horizontal length of the roof along the gutter or ridge.

Slope (Rafter) Length

Typical: 14 to 22 ft

Continuous run length from eave edge to ridge peak.

Panel Coverage Width

Typical: 36 inches (through-fastened) or 16-24 inches (standing seam)

Net installed width between panel seams after overlapping.

Assumptions & Limitations

  • Panels run continuously from eave to ridge without intermediate horizontal lap joints.
  • Fastener estimates assume standard 2 screws per square foot for wind resistance.

Safety & Professional Notes

  • Metal panels have sharp cut edges. Always wear cut-resistant Level 4+ safety gloves. Never handle metal roofing sheets in windy conditions.

Frequently Asked Questions

What is the difference between standing seam and corrugated metal roofing?

Standing seam features concealed clips with raised interlocking seams that hide fasteners from weather exposure. Corrugated or R-panel profiles use exposed screws driven directly through the metal with rubber washers.

What underlayment is required under metal roofing?

High-temperature synthetic underlayment rated to at least 240°F (115°C) is recommended because metal absorbs intense solar thermal heat.

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