Calculators
Metal roofing calculators
Panels, standing seam, screws, trim and cut lists for corrugated, ribbed and standing-seam roofs, and what they cost.
Metal roofing is counted differently from shingles. Panels are ordered by the piece, at the length of the slope they cover, in a width that is wider than the strip of roof each one actually covers because the edges overlap. A 36-inch panel covers 36 inches of eave only after the lap is taken off its 38 or 39 inches of sheet, and a 16-inch standing seam panel covers exactly 16 inches because the seam stands up instead of lying over. Get the coverage width right and the panel count follows.
The second difference is that the length does the work the waste allowance does for shingles. Panels are cut to the slope length plus an overhang at the eave, so there is very little offcut on a plain roof, but every valley, hip and dormer turns full panels into angled cuts. These calculators give you panel counts and lengths per roof section, the screws and clips to fasten them, and the trim pieces that finish the edges.
7 calculators
Metal Roof Panel Calculator
Panels per side, panel length and total area for ribbed or corrugated metal roofing from the eave length, slope and coverage width.
Standing Seam Panel Calculator
Standing seam panels, clips and screws from the eave length, seam spacing, slope and clip spacing, for snap-lock, mechanical and nail-strip systems.
Metal Roof Screws Calculator
Panel screws, stitch screws and bags for an exposed-fastener metal roof from the squares or panels, the purlin spacing and the pattern.
Metal Roof Trim Calculator
Ridge cap, eave, rake, valley and wall trim pieces, closure strips, butyl tape, sealant and trim screws from the edge lengths.
Corrugated Shed Roof Calculator
Corrugated sheets, screws, ridge cap and foam closures for a gable or lean-to shed from its length, width and pitch.
Metal Panel Cut List
Panel counts and lengths for up to four roof sections with their own run and pitch, grouped into order lines, cut to length or from stock.
Metal Roof Cost Calculator
Installed cost range for an exposed-fastener, standing seam or metal shingle roof, with gauge, pitch, storeys, tear-off and region as separate lines.
Guides for this topic
Metal roof panel maths: coverage width, laps and cut lists
Metal panels are counted along the eave and sized up the slope. Get coverage width and panel length right, and the rest of the order follows.
Standing seam vs exposed fastener: quantities, cost and life
Both are metal roofs; they are built, priced and maintained differently. The difference shows up in the screws.
What roofers charge per square, by material and region
Roofers price in squares, and a quote is a stack of per-square figures. Here are the published ranges, where they come from, and what moves a price within them.
Questions people ask
- How many metal panels for a 30 by 40 foot roof?
- Panels run up the slope, so count along the eave. A 40-foot eave with 36-inch coverage panels needs 40 ÷ 3 = 13.3, rounded up to 14 panels per side, 28 for a gable roof. On a 30-foot-wide building at 4/12 pitch the slope is 15 feet of run times 1.054 plus a 2-inch eave overhang, so each panel is about 15 feet 10 inches long.
- How many screws per square of metal roofing?
- Exposed-fastener panels on purlins or battens at 24 inches take about 80 screws per square: five screws across a 36-inch panel at every purlin line, with purlin lines every 2 feet up the slope, plus stitch screws along the side laps every 12 to 24 inches. Manufacturers' guides give the exact pattern for their panel; the calculator takes yours.
- How many standing seam panels do I need?
- Divide the eave length by the seam spacing. A 40-foot eave with 16-inch panels needs 40 × 12 ÷ 16 = 30 panels per side; with 12-inch panels, 40. Each panel is clipped to the deck every 24 inches or so up the slope, so a 16-foot panel takes about 9 clips.
- How many pieces of trim does a metal roof take?
- Trim comes in 10-foot sticks that overlap about 6 inches, so each piece covers roughly 9.5 feet. Ridge cap covers the ridge, eave trim and rake trim cover their edges, and valleys, sidewalls and endwalls each need their own profile. A 40 by 30 gable roof takes 5 pieces of ridge cap, 9 of eave trim and 7 of rake trim before closures and sealant.
- What does a metal roof cost per square?
- Published cost surveys for 2025 put exposed-fastener metal roofing at roughly $800 to $1,500 per square installed and standing seam at $1,200 to $2,500, with tear-off, underlayment, pitch and region moving the figure. The metal roof cost calculator shows the range for your roof with every component as its own line, and you can replace any of the defaults with a real quote.
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