Calculated result
21panels
Metal panels to order
Formula
ROOF-METAL-001L × W × √(1 + (rise ÷ 12)²) × (1 + waste) ÷ net coverage
670.82 ft²
Pitched roof area
737.9 ft²
Area including waste
1.118 ×
Slope multiplier
Roofing calculator
Metal roof calculator
Pitched roof area and whole fixed-panel quantity using net area per selected panel.
By Feroz Sheikh · Formula ROOF-METAL-001 v1.0.0 · Tested formula
Formula
ROOF-METAL-001v1.0.0Project inputs
Enter your measurements. Switching units converts the same project, including coverage and unit rates. Package yields keep the unit printed beside each field.
Refine measurements and rates at any time. Your current values are included in the material-list PDF.
Planning estimate, not engineering advice. Confirm site measurements and product specifications. Calculation limits.
This calculator returns pitched roof area and whole metal panels from length, width, rise-per-12 and the panel's net coverage. Formula ROOF-METAL-001 v1.0.0. Pitch multiplies the footprint. Trim and fasteners stay companion lines. Add the panel count to an estimate. Use the approved roof design for structural requirements.
- Measure the horizontal roof length and width.
- Enter rise per 12 and the net area of one fixed-length panel after side laps (net width × ordered length).
- For cut-to-length or site-formed panels, confirm panel layout, coil quantity, trim and fasteners with the manufacturer or supplier.
Size chart
Metal roof chart (6:12, 36 ft² net area per fixed panel, 10% waste)
Enter net area per fixed panel after side laps—not panel width. Cut-to-length systems need a supplier takeoff.
| Footprint | Primary | Check |
|---|---|---|
| 20 × 20 ft | 14 panels | 447.21 ft² |
| 30 × 20 ft | 21 panels | 670.82 ft² |
| 40 × 24 ft | 33 panels | 1073.31 ft² |
| 40 × 30 ft | 41 panels | 1341.64 ft² |
Metric example — 9 × 6 m footprint. A 9 × 6 m footprint at 6:12 and 3.3 m² panel coverage with 10% waste returns 21 panels.
- Panel coverage. Net panel coverage is a product input after laps and ribs. Trim and fasteners stay extras. Sheffield Metals — material estimation
Add your project costs
Enter supplier prices and any labour, equipment or delivery costs. Pick a currency — badges, inputs, and totals follow.
Costs use the square, bundle or panel rate you type. Construclytic does not fetch shingle or metal prices. Tear-off, dumpsters, starter and flashing stay separate estimate lines. For GCC projects, select QAR, AED, SAR, KWD, OMR or BHD and enter local supplier rates.
How this calculator works
A transparent metal roof calculator takeoff.
Feroz SheikhWritten by Feroz Sheikh · founder
This calculator applies roof pitch to horizontal dimensions, then divides the adjusted area by the net area of one selected fixed-length panel after a visible allowance.
This fixed-panel estimate uses the net area covered by one selected fixed-length panel after side laps, not the shingle square or panel width. Pitch still multiplies the footprint. Trim, fasteners and closures remain separate lines.
Worked example. Example: a 30 ft × 20 ft roof at 6:12 has about 671 ft² of slope-adjusted area. With 10% waste and 36 ft² of net area per fixed panel, it rounds to 21 panels.
See the example inputs and calculated result
This separate example uses the calculator's starting values in imperial units. It stays unchanged when you edit the tool above. Example rates, yields and dimensions are assumptions, not recommendations for your project.
| Input | Example value |
|---|---|
| Roof length | 30 ft |
| Roof width | 20 ft |
| Pitch rise | 6 rise per 12 |
| Net area per fixed panel | 36 ft² |
| Waste factor | 10 % |
Example result: Metal panels to order — 21 panels.
L × W × √(1 + (rise ÷ 12)²) × (1 + waste) ÷ net coverage
Use the labelled units above when reproducing this example. To work in metric, switch the calculator to Metric; applicable measurements are converted, while product-specific units remain labelled.
- 1. Measure the horizontal roof length and width.
- 2. Enter rise per 12 and the net area of one fixed-length panel after side laps (net width × ordered length).
- 3. For cut-to-length or site-formed panels, confirm panel layout, coil quantity, trim and fasteners with the manufacturer or supplier.
Field notes that change the number
- Enter net area per fixed panel: installed coverage width × ordered panel length.
- Do not enter a width such as 36 in as though it were 36 ft².
- Cut-to-length and site-formed panels need a profile-specific layout and coil takeoff from the manufacturer or supplier.
Common mistakes
- Using asphalt-shingle squares or panel width in the area-per-panel field.
- Ignoring the pitch multiplier on a 4:12 or steeper.
- Treating an area-based fixed-panel estimate as a cut-to-length layout or complete roof kit.
Need the broader workflow? Read the roofing planning guide.
Questions
Questions about metal roof calculator
Does this estimate trim or fasteners?
No. The fixed-panel area input estimates primary roof panels only; trim and accessories require their own takeoff.
Can I enter panel width in the coverage field?
No. Enter area covered by one fixed-length panel after side laps. Cut-to-length and site-formed systems need a profile-specific supplier takeoff.
How do I calculate metal roofing?
A 30 × 20 ft footprint at 6:12 with 36 ft² net panel coverage and 10% waste returns 21 panels. Enter the manufacturer’s net coverage, not advertised panel width.
Is a metal roof ordered in shingle squares?
No. Metal is net panel coverage after ribs and laps. Shingle squares belong on the asphalt calculator.
What is the formula ID?
This metal roof calculator publishes formula ROOF-METAL-001, version 1.0.0. The ID stays on the result and on the estimate line.