Roof Pitch Chart: Degrees, Slope Factors, and Rafter Lengths

Every standard roof pitch converted to degrees and percent grade, with the slope factor (pitch multiplier) and rafter length per foot of run - all computed from the pitch geometry. Click any pitch for its full page: rafter length tables, hip and valley factors, walkability, and material minimums.

Need your exact rafter length with overhang and birdsmouth cuts? The free rafter calculator draws the whole roof and generates a cut list.

Pitch	Degrees	Grade	Slope factor	Rafter per ft of run
1/12	4.76 deg	8.3%	1.003	12-1/16 in
2/12	9.46 deg	16.7%	1.014	12-3/16 in
3/12	14.04 deg	25%	1.031	12-3/8 in
4/12	18.43 deg	33.3%	1.054	12-5/8 in
5/12	22.62 deg	41.7%	1.083	13 in
6/12	26.57 deg	50%	1.118	13-7/16 in
7/12	30.26 deg	58.3%	1.158	13-7/8 in
8/12	33.69 deg	66.7%	1.202	14-7/16 in
9/12	36.87 deg	75%	1.25	15 in
10/12	39.81 deg	83.3%	1.302	15-5/8 in
11/12	42.51 deg	91.7%	1.357	16-1/4 in
12/12	45 deg	100%	1.414	17 in
14/12	49.4 deg	116.7%	1.537	18-7/16 in
16/12	53.13 deg	133.3%	1.667	20 in
18/12	56.31 deg	150%	1.803	21-5/8 in
24/12	63.43 deg	200%	2.236	26-13/16 in