Roof Pitch & Angle Calculator
Convert a roof pitch to its angle in degrees and slope factor, or work back from an angle to the pitch. Below the calculator is a full roof angle chart for every common pitch.
This free roof pitch calculator converts a roof pitch such as 6/12 into its angle in degrees and slope factor, or works back from an angle to the pitch, with a full roof angle chart for every common pitch below. For a measured report of an actual roof, RoofAngle delivers import-ready ESX and XML from $17, delivered in hours.
Pitch to angle
Multiply your flat footprint area by the slope factor to estimate the actual roof surface area.
Angle to pitch
A standard roof pitch is written as rise over a 12-inch run, so this is the rise for that angle.
Roof angle chart
The angle in degrees and slope factor for every common roof pitch.
| Pitch | Angle | Slope factor | Category |
|---|---|---|---|
| 1:12 | 4.8° | 1.0035 | Low slope |
| 2:12 | 9.5° | 1.0138 | Low slope |
| 3:12 | 14° | 1.0308 | Low slope |
| 4:12 | 18.4° | 1.0541 | Conventional |
| 5:12 | 22.6° | 1.0833 | Conventional |
| 6:12 | 26.6° | 1.118 | Conventional |
| 7:12 | 30.3° | 1.1577 | Conventional |
| 8:12 | 33.7° | 1.2019 | Conventional |
| 9:12 | 36.9° | 1.25 | Conventional |
| 10:12 | 39.8° | 1.3017 | Steep slope |
| 11:12 | 42.5° | 1.3566 | Steep slope |
| 12:12 | 45° | 1.4142 | Steep slope |
Roof angle in degrees to pitch
A quick answer for the most common question: a 20 degree roof angle is about a 4.4:12 pitch, meaning the roof rises roughly 4.4 inches for every 12 inches of run. Use the chart below for other angles, or the calculator above for an exact value.
| Roof angle | Rise per 12" run | Pitch |
|---|---|---|
| 5° | 1" | 1:12 |
| 10° | 2.1" | 2.1:12 |
| 15° | 3.2" | 3.2:12 |
| 20° | 4.4" | 4.4:12 |
| 22.5° | 5" | 5:12 |
| 25° | 5.6" | 5.6:12 |
| 30° | 6.9" | 6.9:12 |
| 35° | 8.4" | 8.4:12 |
| 40° | 10.1" | 10.1:12 |
| 45° | 12" | 12:12 |
How to work out the pitch of a roof
The pitch of a roof is a rise-over-run ratio. The calculator at the top of this page does both conversions for you.
Divide the rise by the run
Measure how much the roof rises vertically, measure the horizontal run below it, then divide the rise by the run. Roofers normalize the run to 12 inches: if a roof rises 6 inches over a 12-inch run, the rise-run ratio is 6:12.
Angle to pitch
Going the other way, from an angle in degrees to a pitch, multiply the tangent of the angle by 12. That gives the rise for a 12-inch run, which is the pitch.
Why slope matters
Steeper slopes shed water and snow faster, need more safety equipment to walk, and change which roofing material is appropriate. Many shingle manufacturers set minimum pitches, and low-slope roofs need membrane systems instead.
Slope factor for area
Slope increases the true surface area, which is why estimates multiply the footprint by a slope factor instead of using the flat plan area.
What is roof pitch and how is it measured?
Roof pitch describes how steep a roof is. It is written as the vertical rise over a 12-inch horizontal run.
6:12 is about 26.57°
A 6:12 pitch rises 6 inches for every 12 inches you move across the roof. The roof angle in degrees is the arctangent of the rise divided by 12, which is why a 6:12 pitch works out to about 26.57 degrees.
Slope factor
The slope factor converts a roof's flat footprint into its true sloped surface area. It equals the square root of the rise squared plus 144, divided by 12. Multiply the footprint by that number for material takeoffs and estimates.
Typical home pitches
Most homes sit between 4:12 and 9:12. Anything above 9:12 is considered a steep-slope roof that usually needs extra safety equipment to measure by hand.
When you need a report
Reading pitch from the ground is fine for a rough idea. A claim or material order needs exact facet areas, edge lengths, and pitch per facet from a roof measurement report, delivered as ESX for Xactimate or XML for Symbility.
Roof Pitch FAQs
Need exact roof measurements, not just the pitch?
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