Most roofs in america follow these dimensions where pitch range is kept between 3 to 7 1 2.
Standard roof pitch for a garage.
Pitches lower than 4 12 have a slight angle and they are defined as low slope roofs.
A ratio is the most common way of expressing roof pitch or roof slope but degrees are also possible.
The most commonly used roof pitches fall in a range between 4 12 and 9 12.
Pitches above 9 12 are very highly angled and are designated steep slope roofs.
Roof pitch is the measurement of roof steepness.
Pitches of less than 2 12 are considered flat roofs even though they may be very slightly angled.
Roof pitch or slope is a measure of vertical rise to horizontal run expressed in inches per foot.
This measurement is best done on a bare roof because curled up roofing shingles will impair your measurement.
The way pitch also known as roof slope is measured is rise over run.
A a roof with a 6 rise for every 12 run has a 6 per foot or 6 in 12 pitch.
The picture below shows the pitch of a 7 12 roof slope meaning that for 12 of horizontal measurement roof run the vertical measurement roof rise is 7.
So if your roof rises 4 inches for every 12 inches of horizontal length then the pitch of your roof is expressed as 4 12.
In the roofing trade the go to term is pitch and it is expressed in terms of 12 inches so the pitch of a roof is determined by how many inches the slope rises for every 12 inches it runs horizontally.