Measure the vertical rise over a 12-inch horizontal run
Use a level and tape measure to find the rise
Place one end of the level on the roof and make it level
Measure straight down from the 12-inch mark on the level to the roof surface
Record the rise in inches
Write the pitch as rise over 12, such as 6/12
Convert the rise to an angle if needed using a roof pitch chart or calculator
Use a pitch gauge or inclinometer for a direct reading
Check multiple spots on the roof for consistency
Use safe roof access and proper fall protection