Metal Roof Calculator
Thirty feet on the ridge and a 24 foot span, overhang 1 ft each side and rise 6, is 930.20 ft², 44 panels at the example 36 by 12 size, 745 screws at the example rate, and 154.14 ft of trim.
Last updated . Gable length starts at thirty feet. Span starts at 24 ft. Overhang starts at 1 ft. Rise starts at 6.
A metal roof calculator for one gable. Area comes from the footprint, the overhang, and the unrounded pitch root. Panels come from the coverage width and the panel length you type. Screws follow a rate you can replace. Trim is eaves, ridge, and rakes.
Squares from the same kind of footprint: roofing calculator. Sheathing sheets: plywood calculator.
Gable panels and trim
This is a simple gable: two slopes, one ridge, two eaves, four rakes. 36 inches and 12 feet are example panel sizes so the count can be checked. 80 screws per 100 square feet is an example rate sitting in the box, not a brand schedule. Type the coverage width after the lap, not the flat sheet width.
Results
Area, runs, and trim
Length runs with the ridge. Span is eave to eave. Overhang is added on every side, so a 30 by 24 foot building with 1 foot of overhang has a 32 by 26 foot plan, 832 square feet. The slope stretch is the unrounded root of 1 plus (6 ÷ 12) squared, the root of 1.25. Roof area is 832 times that root.
Each slope’s horizontal run is half of 26, which is 13 feet. Slope length is 13 times the same root, 14.53 feet. Coverage width tiles the eave: 32 ÷ 3 feet is 10.666…, which rounds up to 11 runs on one slope and 22 on both. Panel length tiles the slope: 14.53 ÷ 12 rounds up to 2 panels in each run, 44 panels. That is a count of pieces, not roof area divided by a rectangle of sheet.
Screws are the roof area times the rate you type, divided by 100, then rounded up. At the example 80, that is 745. Eave trim is 2 × 32. Ridge trim is 32. Rake trim is 4 × 14.53 feet. The three pieces add to 154.14 feet.
Worked gable
| Line | Result |
|---|---|
| Roof area | 930.20 ft² · 86.42 m² |
| Slope length | 14.53 ft · 4.43 m |
| Runs, both slopes | 22 |
| Panels per run | 2 |
| Panels | 44 |
| Screws at 80 per 100 ft² | 745 |
| Eave trim | 64.00 ft · 19.51 m |
| Ridge trim | 32.00 ft · 9.75 m |
| Rake trim | 58.14 ft · 17.72 m |
| Trim, total | 154.14 ft · 46.98 m |
Metal roof questions
What does the 30 by 24 gable return?
Leave length 30 ft, span 24 ft, overhang 1 ft, and rise 6. Roof area reads 930.20 ft² · 86.42 m². Slope length reads 14.53 ft · 4.43 m. With the example 36 in coverage and 12 ft panels, runs read 22, panels per run read 2, and panels read 44. Screws read 745. Eave trim reads 64.00 ft · 19.51 m. Ridge trim reads 32.00 ft · 9.75 m. Rake trim reads 58.14 ft · 17.72 m. Trim, total reads 154.14 ft · 46.98 m.
Why is the area 930.20 and not 930.18?
The grown footprint is 32 by 26, which is 832. The multiplier is the unrounded root of 1.25. 832 times that root is 930.20 square feet. Multiplying 832 by a root chopped at 1.118 would print 930.18, and this form does not do that.
What changes if the coverage width is 16 inches?
Leave the footprint, overhang, pitch, panel length, and screw rate. Set panel coverage width to 16 in. Area, slope, screws, and trim stay put. Runs, both slopes reads 48. Panels per run stays 2. Panels reads 96.
What if the pitch is flat?
Set rise per 12 to 0 and leave the rest. Roof area reads 832.00 ft² · 77.30 m². Slope length reads 13.00 ft · 3.96 m. Runs stay 22, panels per run stay 2, and panels stay 44. Screws reads 666. Eave trim stays 64.00 ft · 19.51 m. Ridge trim stays 32.00 ft · 9.75 m. Rake trim reads 52.00 ft · 15.85 m. Trim, total reads 148.00 ft · 45.11 m.
What if the screw box is cleared?
Clear the example screws per 100 ft² and leave the roof dimensions. Roof area still reads 930.20 ft² · 86.42 m². Screws reads Enter a screw rate. The 80 in that box is only an example so the screw line can be checked.
What if the panel size is cleared?
Clear panel coverage width or panel length. Roof area, slope length, and trim still calculate. Runs, panels per run, and panels each read Enter a panel size.
Is this a hip, and where do the trim lengths come from?
No. It is one gable, two slopes. Eave trim is twice the ridge-direction length after overhang. Ridge trim is that length once. Rake trim is four times the slope length. Hips, valleys, and a second ridge are not in the trim.