### 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