Roof Pitch Calculator
Convert between roof pitch formats: X/12 notation, degrees, and percentage slope. Enter rise and run to get all three formats instantly.
Frequently Asked Questions
What does a 4/12 roof pitch mean?
A 4/12 pitch means the roof rises 4 inches for every 12 inches of horizontal run. It equals about 18.4 degrees or a 33% slope.
How do I measure roof pitch without climbing on the roof?
Hold a level horizontally against the rake board, measure 12 inches from the wall, then measure straight up to the underside of the rafter. That vertical measurement is your rise.
What is the minimum pitch for asphalt shingles?
Most shingle manufacturers require a minimum 2/12 pitch (about 9.5 degrees). Below that, you need a low-slope membrane roofing system.
How do I convert roof pitch to degrees?
Use the formula: degrees = arctan(rise / run). A 6/12 pitch equals arctan(6/12) = arctan(0.5) = 26.6 degrees.
What are common roof pitches for different climates?
Snowy climates use steeper pitches like 8/12 to 12/12 to shed snow. Dry climates often use lower pitches of 3/12 to 6/12. Flat or near-flat roofs (under 2/12) are common on commercial buildings.