The hip and valley factor is determined by finding the square root of ((rise/run)² + 2).

Roof Pitch (In Degrees) Hip and Valley Factor
1/12 4.76° 1.4167
2/12 9.46° 1.4240
3/12 14.04° 1.4362
4/12 18.43° 1.4529
5/12 22.62° 1.4743
6/12 26.57° 1.5000
7/12 30.26° 1.5298
8/12 33.69° 1.5635
9/12 36.87° 1.6008
10/12 39.81° 1.6415
11/12 42.51° 1.6853
12/12 45° 1.7321
13/12 47.29° 1.7815
14/12 49.4° 1.8333
15/12 51.34° 1.8874
16/12 53.13° 1.9437
17/12 54.78° 2.0017
18/12 56.31° 2.0616
19/12 57.72° 2.1230
20/12 59.04° 2.1858