Roof Pitch Calculator
Convert rise and run into roof pitch and angle. A 6 in 12 pitch is a 26.57 degrees roof angle with a 1.118 multiplier.
What roof pitch means
Pitch is how many inches the roof rises for every 12 inches of horizontal run. A 6/12 roof rises 6 inches per foot, which is a 26.57 degrees angle and a 50% slope.
Formulas
- Pitch = rise / run x 12
- Angle = arctan(rise / run)
- Pitch multiplier = square root of 1 + (rise / run) squared
- Rafter length = half the span x multiplier (add overhang separately)
For a 24 ft wide building, each rafter is 13.42 ft before overhang. Multiply any footprint area by the multiplier to get roof surface area, or use the roofing calculator to go straight to squares and cost.
Common pitches
Low slope is under 4/12, conventional is 4/12 to 9/12 and steep is above 9/12. Roofs under 2/12 need special membrane roofing instead of shingles.
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Frequently asked questions
How do I calculate roof pitch?
Divide rise by run and multiply by 12. Measure rise over any run, such as 6 inches up over 12 inches across.
What is the angle of a 6/12 roof?
About 26.57 degrees.
What is the minimum pitch for shingles?
Asphalt shingles need at least 2/12, and 4/12 or more is recommended.
What is a 4/12 pitch in degrees?
About 18.43 degrees.
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