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Metal Roof Panel Calculator

Count standing-seam or corrugated panels for a roof slope, allowing for side laps and the ridge overlap.

  • Answers as you type
  • Every formula cited
  • Calculated in your browser
SettingsSettings for this calculationUS
Market
Imperial · sales tax
Length along the eave, per slope.

Measure each slope separately — a roof with unequal sides needs two runs of this calculation.

Sloped distance from eave to ridge.

The true sloped length, not the horizontal run. Add the eave overhang and any allowance the panel profile needs at the ridge.

Net width after the side lap.

Use the coverage width the manufacturer publishes, not the overall panel width. A 470 mm panel with a 13 mm lap covers 457 mm, and ordering against the wider figure leaves the last panel short.

Panels required

26 panels per slope

High confidence

Counts full-length panels on a rectangular slope. Ridge caps, eave and gable trims, closures and fixings are separate items.

Panel length required
16.5 ft
Total linear panel
429 ft
Slope area
643.5 sq ft
Both slopes
52 panels
Coverage of the last panel used
0 ft
Then change the inputs to see how far the answer moves.

Show calculation logic

How this was calculated

Formula source(s)

  • Panel coverage width is the net width after the side lap, and is what manufacturers publish for ordering
  • MCA (Metal Construction Association) installation guidance: panels are run full length from eave to ridge wherever possible to avoid an end lap

Inputs used

Eave length
39 ft
Eave-to-ridge length
16.5 ft
Panel coverage width
18 in

Intermediate steps

Panel length required
16.5 ft
Total linear panel
429 ft
Slope area
643.5 sq ft
Both slopes
52 panels
Coverage of the last panel used
0 ft
Final result26 panels per slope

Confidence note: Counts full-length panels on a rectangular slope. Ridge caps, eave and gable trims, closures and fixings are separate items.

What this calculation does not cover

  • Assumes each panel runs the full eave-to-ridge length. Above the manufacturer's maximum length an end lap is required, which adds material and detailing.
  • Hips, valleys and dormers are not counted; each generates raking cuts and additional flashing.

Add the equipment this sizes

This result is a specification — 26 panels per slope — not a quantity. Put the thing it sizes into your project: how many, what you call it, and your supplier’s price.

The roof slope at true size, 39′ along the eave by 16′ 6″ from eave to ridge, with 25 panel seam(s) drawn across it.39′16′ 6″

Part of a bigger job

This trade is one line of a job takeoff. Run the whole job and every other trade comes back with it, off the same measurements.

Computed in your browser — nothing you enter is uploaded. Presented in US customary units and US trade terminology. Where a formula follows a published standard, that standard and its edition are cited beside it on this page; where none governs, the page says so. Local amendments override model codes — verify against the code in force where you build.

Sources checked 2026-09-02 · in the site-wide review of 2026-09-06 · v1.0.1

Regulatory standards & verification citations2
  1. Panel coverage width is the net width after the side lap, and is what manufacturers publish for ordering
  2. MCA (Metal Construction Association) installation guidance: panels are run full length from eave to ridge wherever possible to avoid an end lap
Cite this page

Your workspace

Most jobs need more than one number. Add the calculators you need next and they open right here, underneath this one — your figures stay on screen and nothing is lost to a page change.

Tools and safety for this job

To fix roof sheeting and soffit panels. Generic types, no brands, no prices.

Protection this work requires

  • Most fatal falls on small jobs are from under three metres: use a tower or a ladder tied at the top, and never work off the top two rungs.
  • Knives cause more site injuries than any power tool: cut away from your body, change blades often, and wear cut-resistant gloves to EN 388 level C for repeated cutting.

Fix roof sheeting and soffit panels: Roof work is the commonest cause of serious fall injury on domestic sites, and profiled sheeting adds a danger of its own: older fibre-cement and plastic sheets, and the rooflights set among them, can give way under a person's weight without warning. Edge protection or a properly erected tower is the equipment that matters most here, and a roof that is fragile, steep, high or wet is a job for a roofer with the right access and staging, not a longer ladder.

Show the 6 tools this job needs

Essential

  • Chalk line

  • Extension ladder

  • Impact driver

  • Metal snips

  • Tape measure

  • Tower scaffold or trestles

Also needed as materials: chalk refill, impact driver bits.

what each roofing tool is for, and the spec that decides which to buy where one does.

Now that you have the number

These guides cover the work this quantity is for — the first ones run this calculator inside the section that raises the question.

Still deciding? Metal Roof vs Shingles · Clay Tile vs Metal Roof — the factors that actually differ, with no invented prices.

The data behind it: Production rates by operation

How to calculate metal roof panel in 4 steps

  1. Eave lengthLength along the eave, per slope.
  2. Eave-to-ridge lengthSloped distance from eave to ridge.
  3. Panel coverage widthNet width after the side lap.
  4. Panels requiredThe tool computes the panels required from those figures and shows the formula, its sources, and a confidence rating alongside it.

Panels required by eave length

Page defaults, not your figures above.

Eave lengthPanels required (panels per slope)
20 ft14
30 ft21
40 ft27
50 ft34
60 ft41
70 ft47

Frequently asked questions

Coverage width or panel width?
Always coverage. The overall width includes the part that disappears under the next panel's side lap. A 470 mm panel covering 457 mm is 3% narrower in use, and ordering against the overall width leaves the last run short on a wide roof.
Should panels run the full length of the slope?
Wherever the manufacturer's maximum length allows. An end lap is a detail that has to be sealed and fixed correctly, and it is the most common place a metal roof leaks. Long single panels also expand and contract as one piece, which is why the fixing method matters more as they get longer.
Does this include the ridge and trims?
No — panels only. Ridge caps, eave trim, gable or barge trim, valley flashing, closures and the correct fixings are separate and together are a substantial share of a metal roof's material cost.
Preliminary estimate, not certified engineering. This tool produces an indicative quantity calculation for planning purposes only — it is not a certified structural analysis, a guaranteed material takeoff, or a substitute for building department approval. Always verify measurements on-site and have a licensed contractor or structural engineer review any load-bearing, code-sensitive, or safety-critical work before purchasing materials or starting construction. Spotted an arithmetic or standards error? Report it to contact@craftquantities.com with your inputs — a confirmed fix gets a permanent check of its own, so the same mistake cannot come back.