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21/12 roof pitch in degrees

A 21-in-12 roof — 21 inches of rise for every 12 inches of run — as an angle, a percent grade, a slope ratio, and the rafter length it adds per foot of run.

21/12 pitch =

=60.26°

Angle

60.26°

Percent grade

175%

Slope ratio

1.75

Rafter / ft of run

2' 0-3/16"

What it means on the roof

Set a speed square to 60.26° for the plumb and seat cuts. Every foot of horizontal run adds 2' 0-3/16" of common-rafter length, so a run of 10 ft makes a rafter about ten times that. The percent grade (175%) is the same slope a road sign or a laser level reads.

Nearby pitches

Pitches around 21/12

Pitch	Angle	Grade	Rafter / ft run
18/12	56.31°	150%	1' 9-5/8"
19/12	57.72°	158.3333%	1' 10-1/2"
20/12	59.04°	166.6667%	1' 11-5/16"
21/12	60.26°	175%	2' 0-3/16"
22/12	61.39°	183.3333%	2' 1-1/16"
23/12	62.45°	191.6667%	2' 1-15/16"
24/12	63.43°	200%	2' 2-13/16"

All roof pitches Open the calculator

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