If you re not sure what the slope of your roof is and you want to determine that in either degrees or rise in run we recommend this slope finder on amazon.
Roof slope conversion chart.
Use the following formula which also describes a right triangle.
To obtain an accurate roof pitch measurement properly measure the rise and run.
First convert the pitch to a slope.
Two most common methods 4 12 or 4 12 are used for marking the pitch of a roof.
Approximately 8 9 16 in 12.
Here are the equations you may use to solve for the length of the slope and the rafter.
To find the angle of a roof in degrees convert the pitch to a slope then convert to degrees by finding the arc tangent of the slope.
Giving you a slope of 8 556 in 12 or.
To do this simply convert the rise and run as a fraction to a decimal form eg.
Rise run rise run slope.
Rafter rise run this formula is from the pythagorean theorem.
Using a tape measure make a pencil mark 12 inches from the end of a carpenter s level.
You can also calculate roof pitch even without using a roof slope calculator.
0 713 x 12 8 556.
It s very inexpensive and very accurate.
On blue prints architects engineers usually display the pitch of a roof in the format shown on the image where number 4 represents a rise and number 12 represents a length.