What is Roof Pitch?

Roof pitch is a mathematical expression of how steep your roof is. When using pitch, the slope of the roof is given as a ratio of the vertical rise to the horizontal run.

Traditionally, this expression of roof pitch takes the form “X:12” or “X-in-12”.

12 is always used for the run because there are 12 inches in a foot, and you are stating how many inches the roof rises over a one foot span.

The steepness of a roof may also be given in degrees or as a percentage (see Three Ways to Express Roof Slope).

Why Roof Pitch is Important

  1. The pitch of a roof determines what roofing materials can be used on the roof (see Minimum Roof Pitch for Every Roofing Material).

  2. The pitch of a roof is an important factor in figuring out how much roofing material will be needed when installing a new roof, because it allows you to accurately calculate the surface area of the roof (see How to Find the Area of a Roof).

  3. The pitch of a roof is important when making certain roof drainage calculations (see Roof Drainage).

  4. The pitch of a roof determines the roof slope factor, also called the roof slope multiplier, which is used to calculate proper rafter length as well as roof area.

  5. The pitch of a roof determines the hip and valley factor, which is used to calculate the proper length of hip and valley rafters.

More Roof Pitch Pages

See our Roof Pitch Multiplier Chart for a much longer list of roof slope factors, including slope factors for roof pitches by the half-inch. We also explain the math behind the multiplier.

See our Hip and Valley Factor Chart for a much longer list of hip and valley factors, including hip and valley factors for roof pitches by the half-inch. We also explain the math behind the factor.

Convert Degrees to Roof Pitch (X-in-12) converts slopes from 1 to 72 degrees into standard roof pitch.

Convert Roof Pitch to Degrees goes in the other direction.

Roof Pitch Chart

Roof Pitch Chart
Pitch of Roof Roof Slope in Degrees Roof Slope Factor Hip and Valley Factor
¼:12 1.193° 1.0002 1.4144
½:12 2.386° 1.001 1.4148
1:12 4.76° 1.003 1.4167
2:12 9.46° 1.014 1.4240
3:12 14.04° 1.031 1.4362
4:12 18.43° 1.054 1.4529
5:12 22.62° 1.083 1.4743
6:12 26.57° 1.118 1.5
7:12 30.26° 1.158 1.5298
8:12 33.69° 1.202 1.5635
9:12 36.87° 1.250 1.6008
10:12 39.81° 1.302 1.6415
11:12 42.51° 1.357 1.6853
12:12 45° 1.414 1.7321
13:12 47.29° 1.474 1.7815
14:12 49.4° 1.537 1.8333
15:12 51.34° 1.601 1.8874
16:12 53.13° 1.667 1.9437
17:12 54.78° 1.734 2.0017
18:12 56.31° 1.803 2.0616