Roof pitch calculator and metal roof panel count
The short answer
Roof pitch is the inches a roof rises for every 12 inches it runs level: rise divided by run, times 12. A roof that rises 6 inches in 12 is a 6 in 12 pitch, about 26.6 degrees.
Roof pitch calculator
Use this roof pitch calculator to turn a rise and run into a pitch and angle, or to count metal roof panels.
Your numbers
Your answer
6 in 12
That roof has a pitch of 6 in 12, about 26.6 degrees.
- Pitch6 in 12
- Angle26.6 degrees
- Slope50%
Its slope is 50%, and the sloped roof is 1.118 times as long as its flat run.
At a glance
- Pitch is written as
- Rise in 12
- A 6 in 12 roof
- 26.6 degrees
- A 12 in 12 roof
- 45 degrees
- Low-slope roof
- 4 in 12 or lessFederal definition
How the roof pitch calculator works
Roof pitch is how many inches the roof rises for every 12 inches it runs level. The calculator uses the geometry of a right triangle.
- Pitch: rise divided by run, times 12. A roof that rises 6 inches over 12 inches of run is a 6 in 12 pitch.
- Angle: the arctangent of the pitch divided by 12.
- Slope factor: the square root of 1 plus (pitch / 12) squared. Multiply a level run by it to get the length along the roof.
- Panel length: the run from eave to ridge, overhang included, times the slope factor, rounded up to the inch.
- Panels: the length along the eave in inches divided by the panel's coverage width, rounded up, times the number of roof sides.
What it assumes
- A plain gable or shed roof with straight edges. Valleys, hips and dormers need extra panels and trim.
- Panels run in one piece from the eave to the ridge. Long runs are sometimes split, with an overlap.
- The coverage width is what one panel covers once it is lapped onto the next. The calculator starts at 36 inches; check your panel's spec sheet.
- No extra for waste, trim, ridge cap or flashing.
Roof pitch chart: angle and slope factor
| Pitch | Angle | Slope factor |
|---|---|---|
| 2 in 12 | 9.5° | 1.014 |
| 3 in 12 | 14° | 1.031 |
| 4 in 12 | 18.4° | 1.054 |
| 5 in 12 | 22.6° | 1.083 |
| 6 in 12 | 26.6° | 1.118 |
| 7 in 12 | 30.3° | 1.158 |
| 8 in 12 | 33.7° | 1.202 |
| 9 in 12 | 36.9° | 1.250 |
| 10 in 12 | 39.8° | 1.302 |
| 12 in 12 | 45° | 1.414 |
So a 4 in 12 roof is about 18.4 degrees, and a 12 in 12 roof is 45 degrees, rising a foot for every foot it runs.
Metal roof calculator: how many panels
For a metal roof you need two numbers: how long each panel is, and how many fit across the roof. Switch the calculator to "Metal roof panels" to get both.
A Bonners Ferry example
Say you are putting a metal roof on a 40-foot shop near Bonners Ferry. It is a 6 in 12 gable roof. The run from the eave to the ridge is 15 feet with the overhang, and the panels cover 36 inches each.
- Slope factor for 6 in 12: the square root of (1 + 0.5 x 0.5) = 1.118.
- Panel length: 15 x 1.118 = 16.77 feet = 201.25 inches, so 16 ft 10 in panels.
- Panels a side: 40 x 12 = 480 inches / 36 = 13.3, so 14 panels.
- Two sides: 14 x 2 = 28 panels, covering about 1,342 square feet.
Facts this tool uses
| Fact | Figure | Source |
|---|---|---|
| How roof slope is written | Inches of rise in 12 of run (vertical to horizontal) | 29 CFR 1926.500, definitions (Cornell Law School, Legal Information Institute)Low-slope and steep roof definitions checked Oct 28, 2026 |
| Low-slope roof | A slope of 4 in 12 or less | 29 CFR 1926.500, definitions (Cornell Law School, Legal Information Institute)Low-slope roof definition checked Oct 28, 2026 |
| Steep roof | A slope greater than 4 in 12 | 29 CFR 1926.500, definitions (Cornell Law School, Legal Information Institute)Steep roof definition checked Oct 28, 2026 |
Next step
Ready to have it put on? Roofing businesses in Bonners Ferry