How to Find Your Roof Pitch: Two Easy Ways

You need a level, a tape measure and about five minutes. If you would rather stay off the roof, the attic method works just as well.

Method 1: level and tape on the roof or a rafter

1. Mark 12 inches from one end of a level (or use a 12-inch speed square).
2. Rest that end on the roof surface (or against the bottom edge of a rafter in the attic) and hold the level perfectly flat.
3. At the 12-inch mark, measure straight down to the roof or rafter. That number is your rise. 6 inches means a 6/12 pitch.

If your level is longer, measure at 24 inches and divide the rise by 2. Short on room? Measure over any length and enter both numbers below.

Method 2: measure from the gable end

On a gable roof you can work from the outside without climbing. Measure the full width of the house wall-to-wall (the span) and the height of the ridge above the top of the walls. Half the span is the run.

Ridge height is easiest to get by counting siding courses (multiply by the exposure, often 4 to 7 inches) or measuring inside the attic from the top of the ceiling joists to the underside of the ridge.

From the ground: phone, photo or plans

• Phone inclinometer. Lay the phone on a rafter or the roof edge and read the angle, then convert with pitch to degrees.
• Photo of the gable. Take a straight-on photo of the gable end, then measure the rise and half-width of the triangle on screen in any units. The ratio is what matters.
• Plans. Building plans usually show the pitch as a small triangle symbol with 12 on the horizontal leg.

Safety first: if the roof is steeper than about 6/12, wet, or more than one story up, use the attic or gable method. Fall protection is required for construction work at 6 feet and above.

Common mistakes

• Measuring on a sagging section or across a shingle bump. Use a straight rafter or the flat of a long level.
• Using the full span instead of half the span in method 2. That halves your pitch.
• Assuming every plane is the same. Porches, dormers and additions often have their own pitch.

Last reviewed 2026-10-10. Results are estimates for planning; confirm quantities with your supplier and requirements with your local building code and the manufacturer's instructions.