Roof Pitch Calculator

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.

No pitch is automatically safe to walk. Surface material, moisture, debris, access, condition, height, and fall-protection requirements all matter. Use appropriate fall protection and a qualified roofing professional rather than treating a pitch threshold as permission to step onto the roof.

Asphalt-shingle systems have material-specific minimum slopes and installation conditions. Near the low end of an approved slope range, the manufacturer may require enhanced underlayment or a different roof system. Confirm the adopted code and the exact shingle installation instructions. This calculator converts pitch only and cannot establish roof-system compliance.

The adopted code sets material-specific minimum slopes and installation conditions. They vary by roofing system and local amendment. Do not select a roof system from a pitch conversion alone. Use the manufacturer's tested installation instructions and a qualified roofing professional.

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.