Metal Roofing Material Calculator — Panels, Screws & Full Takeoff
Estimate metal roofing panels, screws or clips, ridge caps, eave/rake trim, closure strips and underlayment rolls for standing-seam or exposed-fastener metal roofs — with pitch-factor geometry, per-plane panel layout, waste kept on its own line, and a cut list for the top row. Free, no sign-up, 100% in your browser.
100% client-side — nothing leaves your browser
Standing seam + exposed fastener
Per-plane layout, not just area
What this tool is (and is not). This is a quantity takeoff tool: it tells you how much material to order — panels, screws, trim, closures, underlayment. It does not price the job: for installed cost with labor, tear-off, repair-vs-replace and financing, see the roof cost lab. For asphalt shingle roofs (bundles, nails — a different unit system), see the roof shingle calculator. To measure your roof’s slope geometry first, see the roof pitch calculator.
Roof shape
Building dimensions
Along the ridge / eave
Span, wall to wall
e.g. 6 = 6/12
Beyond the wall
Beyond the gable wall
Hip roof planes (measure each plane’s eave width and slope length)
× 2 identical planes
Up the slope, incl. overhang
× 2 identical planes
Up the slope, incl. overhang
× 4 hips
Custom planes
Panel
Width covered after sidelap
Overlap between sheet rows
Fasteners & waste
Up the slope, typ. 2 ft
Ribs crossed, typ. 4–5
Up the slope, typ. 2 ft
10% simple, 12–15% hips/valleys
Synthetic 10, felt #15 ≈ 4
Estimates only — confirm the final order with your panel supplier. Fastener schedules vary by manufacturer and wind zone.
Panel coverage & fastener reference
Every metal panel has two widths: the flat sheet width and the installed coverage left after the sidelap engages. Order from installed coverage, always. The table below gives the common defaults — every value is editable in the tool.
| Profile | Fastener style | Installed coverage | Common lengths | Fastener default |
|---|---|---|---|---|
| Standing seam (residential) | Concealed clips | 16 in | Full length, eave to ridge | 1 clip per panel every 24 in up the slope |
| Standing seam (commercial) | Concealed clips | 24 in | Full length, eave to ridge | 1 clip per panel every 24 in up the slope |
| Exposed fastener (R-panel / PBR) | Through-face screws | 36 in | 8–20 ft (12 ft typical) | Screw lines every 24 in; 4–5 screws across each line |
| Corrugated | Through-face screws | 26 in / 36 in | 8–12 ft | Screw lines every 24 in; 3–4 screws across each line |
Pitch factor reference
Slope length = horizontal run × pitch factor. The factor is exact math: √(1 + (rise/12)²).
| Pitch | Factor | Example: 15 ft run → slope |
|---|---|---|
| 3/12 | 1.0308 | 15.46 ft |
| 4/12 | 1.0541 | 15.81 ft |
| 6/12 | 1.1180 | 16.77 ft |
| 8/12 | 1.2019 | 18.03 ft |
| 12/12 | 1.4142 | 21.21 ft |
Pitch table spot-checked against the exact formula √(1+(rise/12)²): 6/12 = 1.1180339…, 4/12 = 1.0540925…
How the math works
A metal roof takeoff is a layout problem, not an area division. Dividing total square footage by panel area silently ignores the round-up at every eave, so it under-orders. The correct sequence:
- 1. Slope length. Measure the horizontal run (half the span plus the eave overhang on a gable), then stretch it up the roof:
slope = run × √(1 + (rise/12)²). A 17 ft run at 6/12 becomes 19.007 ft — not 17 ft. - 2. Panel columns.
columns = ceil(eave width in inches / installed coverage). The eave width includes gable overhangs: a 40 ft building with 1 ft overhangs each end has a 42 ft eave, givingceil(504 / 36) = 14columns per slope. - 3. Rows. Full-length panels: 1 row. Stock sheets:
rows = ceil((slope − end lap) / (stock length − end lap))— the lap is subtracted, not double counted. The top row is cut to the remainder, and the tool reports that cut length. - 4. Spares, kept honest.
spare = ceil(panels × waste%)is added on top of the rounded layout count and shown on its own line — the column round-up is layout, not waste. - 5. Trim. Ridge cap in 10.5 ft pieces over the ridge length (gable: building length + gable overhangs); eave and rake trim in 10 ft sticks; hips capped like ridge; valleys flashed in 10 ft sticks.
- 6. Fasteners. Exposed-fastener: screw lines every 24 in up the slope, screws across each panel’s ribs at every line, plus stitch screws along each sidelap every 12 in. Standing seam: clips every 24 in up the slope per panel, no face screws. Closures: 2 strips per panel column (one outside at the eave, one inside at the ridge).
Worked examples
Each example below is computed live by the same engine the tool runs — paste the inputs to reproduce it.
- Example A — gable, full-length exposed-fastener. 40 × 30 ft building, 6/12 pitch, 2 ft eave overhang, 1 ft gable overhangs, 36 in panels, screw lines every 24 in with 5 screws per line, 10% spare. Run = 15 + 2 = 17 ft; slope = 17 × 1.1180340 = 19.007 ft; eave = 42 ft → 14 columns per slope. 28 panels + 3 spare = 31 to order. Roof area 1,596.55 sq ft = 15.97 squares. Trim: 42 ft ridge → 4 caps; 84 ft eave → 9 sticks; 76.03 ft rake → 8 sticks. Closures: 56. Screws: 1,400 field + 494 stitch = 1,894 (≈ 119 per square). Underlayment: 2 rolls of 10-square synthetic.
- Example B — hip, standing seam 16 in. Main planes 30 ft eave × 16 ft slope (×2), end planes 20 ft × 16 ft (×2), 10 ft ridge, four 18.44 ft hips. Columns: ceil(360/16) = 23 per main plane, ceil(240/16) = 15 per end plane → 76 panels + 8 spare = 84. Clips: floor(16/2)+1 = 9 per panel → 684 clips. Area 1,600 sq ft = 16.00 squares. Trim: ridge 10 ft → 1 cap; hips 73.76 ft → 8 caps; eave 100 ft → 10 sticks. Closures: 152. Underlayment: 2 rolls.
- Example C — stock sheets with end lap. Same 40 × 30 ft gable at 6/12 with no overhangs, 12 ft stock sheets, 6 in end lap. Slope = 15 × 1.1180340 = 16.771 ft. Rows = ceil((16.771 − 0.5) / (12 − 0.5)) = ceil(1.4148) = 2 rows; top row cut = 16.771 − 11.5 = 5.271 ft. 14 columns × 2 rows × 2 slopes = 56 panels + 6 spare = 62. Area 1,341.64 sq ft = 13.42 squares.
All figures above are exact engine outputs (python oracle vs JS engine agree on every digit); intermediate values are rounded for readability.
Ordering tips that save real money
- Confirm coverage with the supplier before ordering. “36 in panel” can mean 36 in flat with 34 in coverage on some imports — a 2 in miss across a 42 ft eave is a full missing column.
- Order full-length panels when the slope allows. One piece per column means zero end laps, zero leak points, and no cut waste on the slope.
- Keep one bundle of spare panels, not a percentage fantasy. A 10% spare on 28 panels is 3 — enough for a miscut and a future repair. On cut-up hips, 15% is the honest number.
- Count screws before the truck arrives. Running out mid-roof means mismatched screw lots and a second delivery fee. The per-square readout tells you at a glance if your count is sane (roughly 70–120 per square for exposed-fastener including stitch screws).
- Closures are cheap; leaks are not. Outside closures at the eave keep wind-driven rain and insects out; inside closures at the ridge stop the same under the cap. Two per column — don’t skip them.
- Underlayment first, panels second. Synthetic underlayment at 10 squares per roll usually beats felt on both labor and coverage — two rolls cover the entire Example A roof.
Frequently asked questions
How many metal roofing panels do I need?
For each rectangular roof plane: columns = ceiling(eave width in inches / installed panel coverage), rows = 1 for full-length panels or ceiling((slope - end lap) / (stock length - end lap)) for stock sheets, then multiply by the number of identical planes and add a spare percentage. Worked example: a 40 x 30 ft gable roof at 6/12 pitch with 2 ft eave and 1 ft gable overhangs gives a 42 ft eave and 19.007 ft slope; at 36 in coverage that is 14 columns per slope, 28 panels, plus 10% spare (3) = order 31 full-length panels.
What is the difference between standing seam and exposed-fastener takeoff?
The panel count math is identical, but the fasteners change completely. Exposed-fastener panels (screwed through the face) need field screws - typically screw lines every 24 in up the slope with 4-5 screws across each panel - plus stitch screws along every sidelap. Standing seam is concealed-fastener: no face screws at all, just clips, typically one clip per panel every 24 in up the slope. Our example gable roof needs 1,894 screws as exposed-fastener, or 684 clips as standing seam with 16 in coverage.
What is installed coverage, and why does it matter?
Installed coverage is the width a panel actually covers on the roof after the sidelap is engaged - always less than the flat sheet width. A classic R-panel may be 39 in wide flat but only covers 36 in once overlapped. Using the raw sheet width in your math under-orders panels: for a 42 ft eave, dividing by 39 gives 13 columns, but you really need 14 columns at 36 in installed coverage. Always use the coverage number printed on the panel label, and every coverage input in this tool is the installed value.
How many screws do I need per square of exposed-fastener metal roof?
Rule of thumb: 70-90 field screws per roofing square (100 sq ft), plus stitch screws along sidelaps. Our worked gable example (1,596.55 sq ft = 15.97 squares, 36 in panels, screw lines every 24 in, 5 screws per line) needs 1,400 field screws - about 88 per square - plus 494 stitch screws, 1,894 total, about 119 per square. Standing-seam roofs need zero face screws; the same example needs 684 clips, about 43 per square.
What are closure strips and how many do I need?
Closures are foam or profiled strips that seal the gap between the panel ribs and the trim. You need outside closures along the eave (under the drip edge) and inside closures along the ridge (under the ridge cap) - one strip per panel column at each end, so 2 strips per column. The example gable roof has 28 panel columns and needs 56 closure strips; the hip example with 76 panels needs 152.
How much waste should I add to a metal roof order?
Add 10% spare panels for a simple gable or shed roof, 12-15% for hips, valleys and cut-up roofs. Important: the column round-up is already layout, not waste - add the spare percentage on top of the rounded panel count, on its own line, so you can see what is layout and what is true spare. This tool keeps them separate: 28 layout panels + 3 spare = 31 to order in the gable example.
How is ridge cap length measured?
For a gable roof it is the building length plus the gable overhangs on both ends. The example: 40 ft + 2 x 1 ft = 42 ft of ridge, sold in 10.5 ft pieces, so 4 pieces. For hips, add the 4 hip lengths (each hip gets its own cap): the hip example has 73.76 ft of hip, which is 8 cap pieces, plus 1 piece for the 10 ft main ridge.
How many underlayment rolls do I need?
Divide the sloped roof area by the coverage of one roll and round up. Synthetic underlayment usually covers 10 squares (1,000 sq ft) per roll; #15 felt covers about 4 squares. The example gable roof is 15.97 squares, so 2 synthetic rolls (or 4 felt rolls). This tool lets you set the roll size, and the count is always rounded up to whole rolls.
Can panels run full length from eave to ridge?
Often yes - that is the ideal, with one piece and no end laps. The limit is transport and handling: many suppliers cap custom lengths around 40-45 ft, and long panels are hard to handle without oil-canning. When the slope is longer than available stock, use stock sheets with a 6 in end lap: the 16.771 ft slope in example C needs 2 rows of 12 ft sheets, with the top row cut to 5.271 ft. The tool shows the cut length for the top row.
What about valleys on a metal roof?
Valleys get W-valley flashing in 10 ft sticks - measure each valley from eave to ridge and enter the total length. The tool converts it to pieces (example: 14 ft of valley = 2 pieces). Valley panels must be cut at an angle, which is exactly why cut-up roofs get the higher 12-15% waste tier. Hip roofs have no valleys, but their triangular planes cut panels at angles too.
I need installed cost, not quantities - where do I go?
This is a quantity takeoff tool: it answers how much material to order. For installed cost with labor, tear-off, repair-vs-replace analysis, insurance modes and financing, use our roof cost lab. For a quick single-plane bundle count from rise and run, the roof pitch calculator has a built-in estimator.
Does this work for shingle roofs?
No - shingles are sold in bundles per square, a completely different unit. Use our roof shingle calculator for bundles, ridge caps, nails and underlayment on asphalt shingle roofs. The two tools are deliberately separate so neither one mixes units: panels and screws here, bundles and nails there.
Related tools: roof cost lab (installed cost, repair-vs-replace, financing) · roof shingle calculator (bundles & nails for asphalt roofs) · roof pitch calculator (slope geometry & rafter math). Estimates only — always confirm the final order with your panel supplier and local code requirements.
Free tool by NRTechStudio