Roof Pitch Calculator
Convert between rise/run, angle, and X/12 roof pitch notation. Tells you if your roof is walkable and what roofing it supports.
Roof measurements
Roof pitch
6/12
26.57 degrees from horizontal. Conventional pitch.
Pitch details:
Angle
26.57°
Slope (decimal)
0.5
Rise per 12 in
6 in
Classification
Conventional
4/12 to 9/12. Standard pitch for most homes. Walkable with caution.
Frequently Asked Questions about the Roof Pitch Calculator
What does X/12 roof pitch notation mean?
X/12 means the roof rises X inches for every 12 inches of horizontal run. A 6/12 pitch rises 6 inches over a 12 inch run, which works out to a 26.57 degree angle.
What roof pitch is walkable?
Anything under 6/12 is walkable for most people in soft-soled shoes. From 6/12 to 8/12 you want a roof harness. Above 9/12 you need roof jacks and fall protection.
What is the minimum pitch for asphalt shingles?
Standard 3-tab and architectural shingles need 2/12 minimum. Between 2/12 and 4/12 you must add a double layer of underlayment or ice and water membrane. Below 2/12 use a membrane roof.
Does building code require a specific pitch?
The IRC sets minimums by roofing material: 2/12 for asphalt shingles with extra underlayment, 3/12 for metal panels, 4/12 for wood shakes, and 0.25/12 for membrane roofs. Local code may go stricter.
How do I convert pitch to degrees?
Divide rise by run, then take the arctangent. A 4/12 pitch is atan(4/12) = 18.43 degrees. A 12/12 pitch (45 degree square) is exactly 45 degrees. The calculator does this for you.