Roof Pitch Calculator
Roof pitch is the rise in inches for every 12 inches of horizontal run. Measure it by holding a level 12 inches long against the roof (or a rafter) and measuring straight up to the roof surface.
Pitch decides which roofing you can use: most shingles need at least 4/12 (2/12 with extra underlayment), and roofs under 2/12 need a membrane.
How it’s calculated
- Pitch = rise ÷ run × 12.
- Angle = arctan(rise ÷ run).
- Roof area multiplier = √(rise² + 12²) ÷ 12.
Every roof pitch
Questions
- What is the most common roof pitch?
- 4/12 to 9/12 covers most homes in the US; 6/12 is very common.
- What angle is a 6/12 roof?
- 26.57 degrees.
- What is a walkable roof pitch?
- Up to about 6/12 most people can walk on safely. 7/12 and steeper needs roof jacks or a harness.