What is an 8/12 roof pitch in degrees?

Data checked October 2026

Short answer

An 8/12 pitch rises 8 inches for every 12 inches of run: 33.69° (a 66.7% grade), with a slope multiplier of 1.202.

Roof area: every 100 sq ft of plan becomes 120.2 sq ft of roof, so a 1,500 sq ft footprint (overhangs included) has 18 squares of roof at 8/12.
Hips and valleys: factor 1.563 — on a 28-ft-wide hip roof each hip is 14 × 1.563 = 21.9 ft long.
Common rafters with 12-in overhangs: 24 ft → 15' 7.5", 28 ft → 18' 0.25", 32 ft → 20' 5.25". On a 28-ft span the ridge sits 9' 4" above the wall plates.
Roofing: Shingles over a single layer of underlayment, and any metal roof.
Steep roof: From 8/12 roofers typically charge $50–100 more per square, and where ice barrier is required it must reach at least 36 in up the slope. Plan on roof jacks or harnesses.

Adjust it to your exact job

What do you know?

Start from

Common pitches

Rise per 12 in of run

/12

Rafter length (optional)

Building widthwall to wall

= 28' · 8.53 m

Overhanglevel

= 1'

Roof pitch

8/12

33.69° · 66.7% grade · slope multiplier 1.202

Angle: 33.69°
Slope multiplier: ×1.202plan area → roof area
Hip / valley factor: ×1.563× half the span = hip length
Grade: 66.7%

Common rafter for a 28' span

Rafter incl. 12-in overhang: 18' 0.25"
Ridge height above the walls: 9' 4"
Wall to ridge (no overhang): 16' 10"
Hip rafter, wall to ridge: 21' 10.75"

(14 ft run + 1 ft overhang) × 1.202. Measured along the top edge; deduct half the ridge-board thickness and allow for the plumb and tail cuts when you lay out the board.

Steep roof

From 8/12 roofers typically charge $50–100 more per square, and where ice barrier is required it must reach at least 36 in up the slope. Plan on roof jacks or harnesses.

What can go on a 8/12 roof?

Minimum slopes by roofing type
Roofing	Minimum	Here
Asphalt shingles	2/12	Yes
36-in rib panel (maker)	2.5/12	Yes
Lapped metal, no sealant (IRC)	3/12	Yes
Lapped metal with lap sealant	0.5/12	Yes
Standing seam metal	0.25/12	Yes

Pitch table

Roof pitch to angle and multipliers
Pitch	Angle	Slope factor	Hip factor
1/12	4.76°	1.003	1.417
2/12	9.46°	1.014	1.424
3/12	14.04°	1.031	1.436
4/12	18.43°	1.054	1.453
5/12	22.62°	1.083	1.474
6/12	26.57°	1.118	1.5
7/12	30.26°	1.158	1.53
8/12	33.69°	1.202	1.563
9/12	36.87°	1.25	1.601
10/12	39.81°	1.302	1.641
11/12	42.51°	1.357	1.685
12/12	45°	1.414	1.732
14/12	49.4°	1.537	1.833
16/12	53.13°	1.667	1.944
18/12	56.31°	1.803	2.062
24/12	63.43°	2.236	2.449

Three safe ways to measure

In the attic: touch one end of a level to the underside of a rafter and hold it level, mark 12 in along it, and measure straight up to the rafter. That number is your pitch.
At the gable end, from a ladder: do the same against the rake board — no need to walk the roof.
With a phone: lay it on the shingles (or a rafter) with a level app and read the angle, then switch this calculator to Angle.

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Compare

Pitches around 8/12

Pitch	Angle	Grade	Multiplier	Hip/valley
6/12	26.57°	50%	1.118	1.5
7/12	30.26°	58.3%	1.158	1.53
8/12	33.69°	66.7%	1.202	1.563
9/12	36.87°	75%	1.25	1.601
10/12	39.81°	83.3%	1.302	1.641

How this was worked out

Angle = arctan(8 ÷ 12) = 33.69°. Slope multiplier = √(1 + (8 ÷ 12)²) = 1.2019. Hip/valley factor = √(2 + (8 ÷ 12)²) = 1.5635, applied to half the building width.

Rafter length is (half the span + the level overhang) × 1.202: for a 28-ft span with a 1-ft overhang, (14 + 1) × 1.202 = 18.03 ft, measured along the top edge before the ridge-board deduction and tail cuts.

The full method, material data and tips are on the main roof pitch calculator page.

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Sources

Data behind this answer

CertainTeed Shingle Applicator's Manual, 17th ed. (Sept 2026) — slope factor (6/12 = 1.118) and hip/valley factor tables · checked October 2026
2024 International Residential Code, Chapter 9 (UpCodes) — minimum slopes: shingles 2:12 (double underlayment below 4:12), lapped metal 3:12, standing seam ¼:12 · checked October 2026
EstimationPro — roofing labor cost per square — 8/12 and steeper priced +$50–100 per square over walkable rates · checked October 2026
Owens Corning Oakridge installation instructions (2026) — over 21 in per ft: 6 nails and 4 spots of roof cement per shingle · checked October 2026

Short answer

An 8/12 pitch rises 8 inches for every 12 inches of run: 33.69° (a 66.7% grade), with a slope multiplier of 1.202.

Roof area: every 100 sq ft of plan becomes 120.2 sq ft of roof, so a 1,500 sq ft footprint (overhangs included) has 18 squares of roof at 8/12.

Hips and valleys: factor 1.563 — on a 28-ft-wide hip roof each hip is 14 × 1.563 = 21.9 ft long.

Common rafters with 12-in overhangs: 24 ft → 15' 7.5", 28 ft → 18' 0.25", 32 ft → 20' 5.25". On a 28-ft span the ridge sits 9' 4" above the wall plates.

Roofing: Shingles over a single layer of underlayment, and any metal roof.

Steep roof: From 8/12 roofers typically charge $50–100 more per square, and where ice barrier is required it must reach at least 36 in up the slope. Plan on roof jacks or harnesses.

Adjust it to your exact job

What do you know?

Start from

Common pitches

Rise per 12 in of run

/12

Rafter length (optional)

Building widthwall to wall

= 28' · 8.53 m

Overhanglevel

= 1'

Roof pitch

8/12

33.69° · 66.7% grade · slope multiplier 1.202

Angle: 33.69°
Slope multiplier: ×1.202plan area → roof area
Hip / valley factor: ×1.563× half the span = hip length
Grade: 66.7%

Common rafter for a 28' span

Rafter incl. 12-in overhang: 18' 0.25"
Ridge height above the walls: 9' 4"
Wall to ridge (no overhang): 16' 10"
Hip rafter, wall to ridge: 21' 10.75"

(14 ft run + 1 ft overhang) × 1.202. Measured along the top edge; deduct half the ridge-board thickness and allow for the plumb and tail cuts when you lay out the board.

Steep roof

From 8/12 roofers typically charge $50–100 more per square, and where ice barrier is required it must reach at least 36 in up the slope. Plan on roof jacks or harnesses.

What can go on a 8/12 roof?

Minimum slopes by roofing type
Roofing	Minimum	Here
Asphalt shingles	2/12	Yes
36-in rib panel (maker)	2.5/12	Yes
Lapped metal, no sealant (IRC)	3/12	Yes
Lapped metal with lap sealant	0.5/12	Yes
Standing seam metal	0.25/12	Yes

Pitch table

Roof pitch to angle and multipliers
Pitch	Angle	Slope factor	Hip factor
1/12	4.76°	1.003	1.417
2/12	9.46°	1.014	1.424
3/12	14.04°	1.031	1.436
4/12	18.43°	1.054	1.453
5/12	22.62°	1.083	1.474
6/12	26.57°	1.118	1.5
7/12	30.26°	1.158	1.53
8/12	33.69°	1.202	1.563
9/12	36.87°	1.25	1.601
10/12	39.81°	1.302	1.641
11/12	42.51°	1.357	1.685
12/12	45°	1.414	1.732
14/12	49.4°	1.537	1.833
16/12	53.13°	1.667	1.944
18/12	56.31°	1.803	2.062
24/12	63.43°	2.236	2.449

Three safe ways to measure

In the attic: touch one end of a level to the underside of a rafter and hold it level, mark 12 in along it, and measure straight up to the rafter. That number is your pitch.
At the gable end, from a ladder: do the same against the rake board — no need to walk the roof.
With a phone: lay it on the shingles (or a rafter) with a level app and read the angle, then switch this calculator to Angle.

Pitch

Angle

Grade

Multiplier

Hip/valley

6/12

26.57°

50%

1.118

1.5

7/12

30.26°

58.3%

1.158

1.53

8/12

33.69°

66.7%

1.202

1.563

9/12

36.87°

75%

1.25

1.601

10/12

39.81°

83.3%

1.302

1.641

How this was worked out

Angle = arctan(8 ÷ 12) = 33.69°. Slope multiplier = √(1 + (8 ÷ 12)²) = 1.2019. Hip/valley factor = √(2 + (8 ÷ 12)²) = 1.5635, applied to half the building width.

The full method, material data and tips are on the main roof pitch calculator page.