Metal Roofing Material Calculator
Enter your measurements
Extra to cover cuts, breakage, and mistakes.
Results
- Panels needed39 panels
- Roofing squares13.91 squares
- Panel coverage36 sq ft each
- Screws1,114
Estimated cost
per sq ft of metal roofing (panels only)
Material range spans bare corrugated steel at the low end to premium painted standing-seam panels at the high end; panels only, no fasteners or trim. Installed range adds fasteners, ridge cap, drip edge, underlayment, and labor — exposed-fastener jobs fall toward $4.50–$8.00 per sq ft installed, while standing seam typically runs $10–$16 per sq ft installed.
Estimate only — prices vary by region, supplier, and season. Get a local quote before buying.
This metal roofing calculator for material estimates the number of panels, roofing squares, and screws you need once you enter your building's footprint, roof pitch, and the panel dimensions you plan to buy. Because metal panels are sold by the individual piece — in fixed coverage widths (commonly 24 or 36 inches) and lengths cut to order or in standard increments — panel count is driven by how each sheet's coverage tiles across your roof, not by a simple square-foot total. The calculator applies a slope multiplier to convert flat footprint area into true roof surface, then divides by the coverage area of one panel and adds your chosen waste factor. A 10% waste allowance is typical for a simple gable roof; bump it to 15% for hips, dormers, or roofs with multiple valleys, where angled cuts leave more unusable offcuts. The screw output uses the standard 80-fasteners-per-square rule for exposed-fastener panels.
How it’s calculated
Roof area = Footprint × slope multiplier. Panels = area ÷ (panel width × length), plus waste. Screws ≈ 80 per square.
Worked example
For a 40-ft by 30-ft building with a 4/12 pitch, using 36-inch-wide by 12-ft panels and a 10% waste factor, the calculator returns 39 panels covering 13.91 roofing squares at 36 sq ft each, plus an estimated 1,114 screws. That screw count matters at ordering time because exposed-fastener panel jobs use roughly 80 screws per square, and buying short means a return trip to the supplier mid-install. Note that 36 inches here is the net coverage width; if your panel's nominal width includes a sidelap, enter the smaller coverage figure so the panel count does not come up short.
Inputs
- Building length
- 40 ft
- Building width
- 30 ft
- Roof pitch (rise per 12)
- 4 /12
- Panel width
- 36 in
- Panel length
- 12 ft
- Waste / overage
- 10 %
Result
- Panels needed
- 39 panels
- Roofing squares
- 13.91 squares
- Panel coverage
- 36 sq ft each
- Screws
- 1,114
- Estimated material cost
- $1,391 – $8,348
Materials & pricing near you
Metal roofing panels are sold by the linear foot, by the panel at a fixed length, or in full squares (100 sq ft) depending on the supplier and product type. Exposed-fastener corrugated and ribbed panels — the budget option — run about $1.00–$3.00 per sq ft for bare or Galvalume steel at big-box stores and roughly $2.50–$4.50 for painted finishes at roofing distributors. Standing-seam panels, which require professional installation, typically run $4.00–$8.00 per sq ft for materials alone. Costs trend higher in metros with elevated freight and labor than in rural areas near a steel rollformer. Minimum delivery orders (often 10–20 squares) apply at most distributors, so small jobs may need pickup or consolidation. In high-wind and coastal zones, local codes may specify panel gauge, fastener type, or uplift ratings, so check with your building department before ordering.
Frequently asked questions
How do I measure my roof footprint for this calculator?
Measure the exterior length and width of the building at ground level, not along the roof slope. The calculator applies the slope multiplier automatically from your pitch entry, so it converts that flat footprint into true roof surface for you. For a simple gable roof, the two footprint dimensions are all you need. For L-shaped or complex plans, break the roof into rectangular sections, calculate each separately, and add the panel counts together.
What panel width should I enter — coverage width or sheet width?
Enter the net coverage width, not the full sheet width. An exposed-fastener panel that is 36 inches wide overall but laps about 1.5 inches under the adjacent panel covers roughly 34.5 inches once installed. Using the full nominal width will undercount the panels you need. Check your panel's spec sheet or ask your supplier for the coverage dimension, which is always listed separately from the nominal sheet width.
Why does the calculator show 80 screws per square?
Eighty screws per square is the standard industry rule of thumb for exposed-fastener metal roofing fastened on roughly 12-inch vertical spacing along each rib. Actual count varies with rib spacing, the fastener pattern, and perimeter trim. For standing-seam panels with concealed clips, fastener counts are far lower and depend on clip spacing, so this screw estimate is most relevant to corrugated and R-panel products.
Can I install a metal roof over my existing shingles?
Often yes, which is one reason metal is popular for reroofs. Many jurisdictions allow a metal panel system over one existing layer of asphalt shingles, sometimes over purlins or a slip sheet, even where a third layer of shingles would not be permitted. But local code, your roof deck's condition, and the panel manufacturer's instructions govern whether an overlay is allowed, so confirm with your building department and pull a permit before starting.