One of the easiest ways to determine the pitch of a roof is to use a pitch-finder tool. Using the tool involves placing it on the roof or gable end soffit or under the rafter in the attic to find the pitch. Even without a pitch-finder tool, the pitch of a roof can be determined with a 48-inch level and a framing square used on top of the roof.
To get the roof pitch using the level and the framing square, the framing square should be placed on the uphill portion of the roof with the tongue facing upwards and with its body level. The level is then placed in plumb position against the roof and the tongue of the framing square.
Measure the distance between the roof at the bottom of the level to the point where the framing square meets the level. The pitch is determined by dividing the distance by two.
When taking roof pitch measurements in this manner, it is necessary to make sure to hold the level firmly against the roof and the tongue of the framing square. Before measuring the distance between the roof and the point where the framing square meets the level, it is best to make sure that the level is plumb.