How do you check roof pitch?

Method 1: From the attic (safest)

1. Find an exposed rafter or the top chord of a truss.
2. Hold a 24 inch level horizontally with one end touching the underside of the rafter.
3. Mark the level at 12 inches from that end.
4. Measure straight up from the 12 inch mark to the rafter. If it is 7 inches, the pitch is 7/12.

Method 2: From a ladder at the gable end

At the rake edge, hold the level against the bottom edge of the rake trim or the roof edge, keep it level, and measure the same way. Make sure the ladder is set at a safe angle and extends above the eave if you need to step off, though for this method you should not need to.

Method 3: On the roof surface

Only on low, walkable roofs in dry weather. Lay a straight board on the shingles first so the bumps of the shingle layers do not skew the reading, then use the level and tape on top of the board.

Method 4: Angle tools

A digital angle gauge, a magnetic protractor, or a phone inclinometer app placed on a rafter gives degrees. Convert by multiplying 12 by the tangent of the angle; for example, 30 degrees is about 6.9/12, so roughly a 7/12 roof.

Check more than one spot

Porches, dormers, and additions often have different pitches than the main roof. For how roofers turn those numbers into roof area, see how roofers measure a roof.