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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 per foot of run, which equals a 26.57-degree angle. The run is always 12 because it gives contractors a consistent reference point without fractions.
What roof pitch is walkable?
Pitches below 6/12 are generally walkable in soft-soled shoes with care. From 6/12 to 8/12 you should use a safety harness. At 9/12 and steeper you need roof jacks and proper fall protection before setting foot on the surface.
What is the minimum pitch for asphalt shingles?
Standard 3-tab and architectural shingles require a minimum of 2/12. At 2/12 to 4/12 you must install a double layer of underlayment or a full ice-and-water shield per manufacturer specs. Below 2/12, the flat range, switch to a fully adhered membrane system instead.
Does building code require a specific pitch?
The IRC sets minimums by material: 2/12 for asphalt shingles with extra underlayment, 3/12 for metal panels, 3/12 for wood shakes, and 0.25/12 for low-slope membrane roofs. Local amendments often go stricter, so verify with your jurisdiction before designing.
How do I convert pitch to degrees?
Divide the rise by 12 to get the decimal slope, then take the arctangent. A 4/12 pitch is atan(4/12) = 18.43 degrees. A 12/12 pitch is exactly 45 degrees. Enter any pitch, angle, or ratio into the calculator and it handles the conversion instantly.