Roof Pitch Calculator
Calculate roof pitch (slope), angle in degrees, and exact rafter length (hypotenuse) based on the rise and run of your roof.
Feet/Inches
Meters/mm
Roofing Expert Tips
1
Understanding Pitch (X/12)
Roof pitch is universally communicated as "inches of rise per 12 inches of run". E.g., a "4/12 pitch" means the roof rises 4 inches for every 1 horizontal foot.
2
Material Limits
Asphalt shingles usually require a minimum pitch of 2/12. If your roof is flatter than 2/12, you must use membrane roofing (EPDM/TPO) instead of shingles to prevent water pooling.
3
Rafter Length
The rafter length calculated is the exact mathematical hypotenuse. Don't forget to add your overhang, and remember to buy lumber slightly longer to allow for plumb cuts.