“It’s a 6/12” means six inches of rise for every twelve inches of run. Carpenters speak pitch. Architects sometimes speak degrees. Homeowners say “pretty steep.”
Those three languages collide at the supply house.
Translate before you order
If you only know the angle from a laser, convert it. If you only know rise over run from a framing plan, convert the other way. The 1/12 roof pitch calculator is for that handshake, not for replacing an engineer on a complex roof.
Why it matters
- Shingle product limits—some materials hate low slopes.
- Safety and staging—walking a 12/12 is a different job than a 4/12.
- Rafter length and birdsmouth layout—wrong pitch, wrong cut, expensive stickers.
Measure run horizontally, not along the rafter, unless you know you’re doing slope distance on purpose. That single confusion has wasted more lumber than bad saws.
When in doubt, crawl the attic with a level and tape, write rise and run on the same photo, and convert once—calmly—on the ground.
Use the 1/12 roof pitch calculator while the numbers are still in front of you.
Launch 1/12 roof pitch calculator →