How to Use the Roof Pitch Calculator
Enter your eave height, ridge height, and the horizontal run between them (all in inches) to get your roof pitch in the standard US X/12 format, along with the equivalent angle in degrees. This is the format used on building plans, roofing quotes, and material calculators across the US.
A roof pitch of 6/12 means the roof rises 6 inches for every 12 inches (1 foot) of horizontal run. Most US homes fall between 4/12 and 9/12 — steeper pitches shed rain and snow faster but require more roofing material and steeper safety precautions during installation.
Roofs under 4/12 are considered low-slope and typically need membrane or built-up roofing rather than standard asphalt shingles, since shallow pitches drain more slowly and are more prone to leaks in heavy rain or snow.
Frequently Asked Questions
It means the roof rises X inches for every 12 inches of horizontal run. A 6/12 pitch rises 6 inches for every foot you move horizontally.
Most residential roofs fall between 4/12 and 9/12. Anything under 4/12 is considered low-slope and often needs special membrane roofing instead of standard shingles.