Metal Roofing Calculator
Metal panels and screws for a roof.
Enter your values
Enter the roof slope length in ft.
Enter the roof width in ft.
Enter the panel coverage width in ft.
Enter the waste allowance in %.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Panels needed
- 15
- Roof area
- 1200 sq ft
- Screws needed (~1.3/sq ft)
- 1,560
- Panel length to order
- 30 ft each
Quick answer
Panel count is roof area divided by the effective coverage width of each panel, plus waste for overlaps and cuts.
panels = ceil(roof width / effective panel coverage width)
At a glance
| What it does | Metal panels and screws for a roof. |
|---|---|
| Category | Home & DIY |
| Inputs needed | Roof slope length, Roof width, Panel coverage width, Waste allowance |
| Main output | Panels needed |
| Formula | panels = ceil(roof width / effective panel coverage width) |
| Cost | Free — no sign-up, no download |
How to use the Metal Roofing Calculator
- 1Measure the sloped roof length (eave to ridge) and the width to be covered.
- 2Check the effective coverage width of your metal panel after overlap.
- 3Add 5-10% waste for hips, valleys and end cuts.
Inputs explained
- Roof slope length(ft)
- Enter the roof slope length in ft.
- Roof width(ft)
- Enter the roof width in ft.
- Panel coverage width(ft)
- Enter the panel coverage width in ft.
- Waste allowance(%)
- Enter the waste allowance in %.
Worked example
Using the values the calculator loads with:
Inputs
- Roof slope length30 ft
- Roof width40 ft
- Panel coverage width3 ft
- Waste allowance10 %
Results
- Panels needed15
- Roof area1200 sq ft
- Screws needed (~1.3/sq ft)1,560
- Panel length to order30 ft each
Frequently asked questions
Do I need underlayment under metal roofing?
Yes, a synthetic or felt underlayment is standard beneath metal panels.
How many screws per panel?
Roughly 1.3-1.5 screws per square foot including ribs and end laps, more at eaves and ridges.
What do I need to enter into the Metal Roofing Calculator?
Just 4 values: roof slope length, roof width, panel coverage width, waste allowance. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the Metal Roofing Calculator work out the answer?
Panel count is roof area divided by the effective coverage width of each panel, plus waste for overlaps and cuts. It applies the formula panels = ceil(roof width / effective panel coverage width) and shows the working so you can check each step by hand.
Is the Metal Roofing Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.