What is a 6/12 roof pitch in degrees?

A 6/12 pitch is 26.6°, from atan(6 ÷ 12). It is also a 50% slope with a pitch factor of 1.118.

What pitch is a 35° roof?

Multiply the tangent of the angle by 12: tan(35°) × 12 = 8.4, so 8.4/12. The nearest whole pitch is 8/12.

Is a 12/12 roof 45 degrees?

Yes. A 12/12 roof rises as much as it runs, which is exactly 45° and a 100% slope.

How steep is a 24/12 pitch?

A 24/12 roof is 63.4° and a 200% slope, with a pitch factor of 2.236. You find it on mansard sides, A-frames and turrets.

Why do degrees rise more slowly on steep roofs?

The angle comes from the arctangent of rise ÷ 12, which flattens out as the pitch grows. Going from 1/12 to 2/12 adds 4.7°, but going from 23/12 to 24/12 adds only 1.0°.

Free converter

Roof pitch to degrees with a full pitch chart

Convert an x/12 pitch to degrees, or a degree reading to x/12, and get the percent slope and pitch factor. The full chart from 1/12 to 24/12 is below.

The formulas

Pitch, degrees and percent are three ways of writing the same slope. Everything goes through the rise per 12 of run.

Pitch to degrees: angle = atan(rise ÷ 12) In degrees, rounded to 0.1.
Degrees to pitch: rise = tan(angle) × 12 Written as rise/12, rounded to 0.1. The nearest whole pitch is that number rounded.
Percent slope: percent = rise ÷ 12 × 100 Rise per 100 of run, rounded to 0.1. Not the same as degrees.
Pitch factor: √(1 + (rise ÷ 12)²) Sloped length per foot of horizontal run. Plan area × pitch factor = true area.

Worked example: both directions

Two conversions from a real job: a porch roof measured at 5½ in of rise per foot, and a main roof read with a phone app at 40°.

Pitch → degrees: the porch is 5.5/12. Rise ÷ 12 = 5.5 ÷ 12 = 0.4583.
Angle = atan(0.4583) = 24.6°. Percent = 0.4583 × 100 = 45.8%.
Pitch factor = √(1 + 0.4583²) = √(1 + 0.2101) = √1.2101 = 1.100.
Degrees → pitch: the app reads 40° on the main roof. tan(40°) = 0.8391, so rise = 0.8391 × 12 = 10.07, which is 10.1/12. Nearest whole pitch: 10/12 (39.8° in the chart).
Percent = 0.8391 × 100 = 83.9%. Pitch factor = √(1 + 0.8391²) = √(1 + 0.7041) = √1.7041 = 1.305.

5.5/12 = 24.6° = 45.8% (factor 1.100); 40° = 10.1/12 = 83.9% (factor 1.305), nearest whole pitch 10/12.

Roof pitch chart: 1/12 to 24/12

Degrees and percent rounded to 0.1, pitch factor to 3 decimals.
Pitch	Degrees	Percent	Pitch factor
1/12	4.8°	8.3%	1.003
2/12	9.5°	16.7%	1.014
3/12	14.0°	25.0%	1.031
4/12	18.4°	33.3%	1.054
5/12	22.6°	41.7%	1.083
6/12	26.6°	50.0%	1.118
7/12	30.3°	58.3%	1.158
8/12	33.7°	66.7%	1.202
9/12	36.9°	75.0%	1.250
10/12	39.8°	83.3%	1.302
11/12	42.5°	91.7%	1.357
12/12	45.0°	100.0%	1.414
13/12	47.3°	108.3%	1.474
14/12	49.4°	116.7%	1.537
15/12	51.3°	125.0%	1.601
16/12	53.1°	133.3%	1.667
17/12	54.8°	141.7%	1.734
18/12	56.3°	150.0%	1.803
19/12	57.7°	158.3%	1.873
20/12	59.0°	166.7%	1.944
21/12	60.3°	175.0%	2.016
22/12	61.4°	183.3%	2.088
23/12	62.4°	191.7%	2.162
24/12	63.4°	200.0%	2.236

How to read the pitch chart

Find your pitch in the first column and read across. A 6/12 roof is 26.6°, a 50% slope, and every foot of horizontal run becomes 1.118 ft along the slope. Going the other way, find the degree reading closest to yours and read the pitch on the left.

Degrees don’t climb evenly. Going from 1/12 to 2/12 adds 4.7°; going from 23/12 to 24/12 adds only 1.0°. On steep roofs a small error in the angle means a big jump in pitch, so take steep readings carefully and more than once.

Degrees, percent and x/12 are not interchangeable

Roofers in North America talk in x/12. Phone apps and digital levels give degrees. Engineered drawings often give a percent slope. All three describe the same roof, but the numbers are very different: 12/12 is 45° and 100%.

The common mix-up is reading a percent as degrees, or the reverse. A 45% slope is a moderate roof; a 45° roof is a 12/12. If a number looks wrong for the house in front of you, check which unit it is before you convert it.

Rounding to a whole pitch, and when not to

Most readings land between whole pitches: a phone app on a rafter rarely shows a clean number. The tool rounds the result to 0.1 and also shows the nearest whole pitch, which is how most people describe and quote a roof.

Use the nearest whole pitch to talk about the roof and to check shingle and underlayment limits. Use the unrounded number when you work out areas, since the pitch factor changes with every tenth. Read the slope on a clean section of the roof, not on a lifted shingle or a ridge cap, and measure additions and dormers on their own.

Steep pitches past 12/12

The chart runs to 24/12 because steep work is real: mansard sides, A-frames, turrets and some dormer faces go well past 45°. At 24/12 the roof is 63.4° and the pitch factor is 2.236, so every square of footprint is more than two squares of shingles. Steep roofs also change how you stage, fasten and waste material, so check the manufacturer’s steep-slope instructions.

Converting one pitch is quick; measuring a whole roof with several planes is where time goes. RoofStruct offers free, unlimited self-serve measuring and PDF reports, no card: trace the facets on satellite imagery, set each pitch, and the true areas and edge lengths are worked out for you.

Roof pitch to degrees questions

What is a 6/12 roof pitch in degrees?: A 6/12 pitch is 26.6°, from atan(6 ÷ 12). It is also a 50% slope with a pitch factor of 1.118.
What pitch is a 35° roof?: Multiply the tangent of the angle by 12: tan(35°) × 12 = 8.4, so 8.4/12. The nearest whole pitch is 8/12.
Is a 12/12 roof 45 degrees?: Yes. A 12/12 roof rises as much as it runs, which is exactly 45° and a 100% slope.
How steep is a 24/12 pitch?: A 24/12 roof is 63.4° and a 200% slope, with a pitch factor of 2.236. You find it on mansard sides, A-frames and turrets.
Why do degrees rise more slowly on steep roofs?: The angle comes from the arctangent of rise ÷ 12, which flattens out as the pitch grows. Going from 1/12 to 2/12 adds 4.7°, but going from 23/12 to 24/12 adds only 1.0°.