Metal Roofing Calculator
Metal roofing lasts 40–70 years compared to 20–25 years for asphalt shingles, and its reflective surface reduces attic heat gain by 25–40% in warm climates. This calculator covers corrugated panels (typically 36" wide) and standing seam (24" wide). Enter roof length, slope length from eave to ridge, number of roof sides, and eave overhang to get total panel count, individual panel length, roofing screws, ridge cap pieces, and closure foam strips needed. Panels run from eave to ridge in a single piece when possible — this minimizes leaks. For runs longer than stock lengths (typically 36 feet), order lap-jointed panels with proper lap sealant. Screws are typically installed at every rib on the eave and ridge rows and every other rib in the field.
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How to Use This Calculator
- 1Enter your measurements in the fields above. Use the units shown next to each field (ft, in, etc.).
- 2Click Calculate to get your material estimate instantly.
- 3Review the highlighted result — it shows the key quantity you need to order.
- 4Use Copy Results to save your estimate, or bookmark the URL — your inputs are encoded in the link.
Pro tip: Always add 10% to your material order to account for waste, cuts, and defects.
Frequently Asked Questions
How many metal roofing panels do I need for a 1,200 sq ft roof?
A 1,200 sq ft roof with standard 36-inch-wide panels that are 20 feet long each (60 sq ft per panel) requires about 20 panels per side. For a two-sided gable roof, that's approximately 40 panels plus 10% extra for trim = 44 panels total.
Can I put metal roofing over existing shingles?
In most jurisdictions, you can install one layer of metal roofing over one existing layer of shingles without tearing off. Check local code — some areas require a tear-off. Install 1×4 furring strips over the shingles to create an air gap and protect the metal panels from shingle granules.
What is the difference between corrugated and standing seam metal roofing?
Corrugated metal panels are cheaper ($1–$3/sq ft) and have exposed fasteners — screws go through the panel face and require neoprene washers to seal. Standing seam panels ($4–$10/sq ft) have hidden fasteners and raised seams that interlock, making them more watertight and suitable for lower pitches. Standing seam is preferred for commercial and high-end residential applications.
How long does metal roofing last?
Steel metal roofing with Galvalume or paint coating lasts 40–60 years. Aluminum panels last 50+ years (especially in coastal areas). Copper and zinc can last 100+ years. Compare this to 20–25 years for standard architectural asphalt shingles. Metal roofing's higher upfront cost typically pays back over the life of the roof.