8/12 Roof Pitch

A 8/12 roof rises 8 inches for every 12 inches of horizontal run: 33.69°, a 66.7% slope, and 20.2% more surface than its footprint.

8/12 pitch at a glance
Measure	8/12 value
Angle	33.69°
Slope percent	66.7%
Rise per foot of run	8 in
Pitch multiplier (area factor)	1.2019
Hip/valley factor	1.5635
Common rafter length per foot of run	14-7/16"
Plumb cut / seat cut	33.7° / 56.3°

Where you see a 8/12 roof

Typical uses: two-story homes, cottages and homes in snow country. An 8/12 roof (33.7 degrees) reads as steep from the street. Snow slides off more readily, and attic space starts to become useful. Most roofers treat it as steep work, with roof jacks or a harness, which adds labor time.

Roof area at 8/12

8/12 formulas

Angle = arctan(8 ÷ 12) = 33.69° Multiplier = √(8² + 12²) ÷ 12 = 1.2019 Roof area = footprint × 1.2019 Rafter = run × 1.2019 Ridge height = run × 8 ÷ 12

Worked examples

Roof area. A 48 × 30 ft house with 1 ft overhangs has a 50 × 32 = 1,600 sq ft footprint. At 8/12: 1,600 × 1.2019 = 1,923 sq ft, or 19.2 squares before waste.

Rafter. A 28 ft span with a 1-1/2" ridge board has a 13.938 ft run. Line length = 13.938 × 1.2019 = 16' 9"; add an 18" overhang (1' 9-5/8" along the slope) for 18' 6-5/8". The ridge sits 9' 4" above the plate line. Try other spans in the rafter calculator.

8/12 rafter lengths and ridge heights

Common rafters at 8/12, measured to the center of the ridge
Building span	Run	Rafter (no overhang)	Ridge rise
16 ft	8 ft	9' 7-3/8"	5' 4"
20 ft	10 ft	12' 1/4"	6' 8"
24 ft	12 ft	14' 5-1/16"	8' 0"
28 ft	14 ft	16' 9-15/16"	9' 4"
32 ft	16 ft	19' 2-3/4"	10' 8"
36 ft	18 ft	21' 7-5/8"	12' 0"

Roof area by footprint at 8/12

Footprint to roof area at 8/12
Footprint (incl. overhang)	Roof area	Squares
1,000 sq ft	1,202 sq ft	12.0
1,500 sq ft	1,803 sq ft	18.0
2,000 sq ft	2,404 sq ft	24.0
2,500 sq ft	3,005 sq ft	30.0
3,000 sq ft	3,606 sq ft	36.1

Materials and walkability

Shingles: Yes. 4/12 and steeper takes a standard shingle installation.
Walkable? With care. Many roofers use toe boards or roof jacks at this pitch.

← 7/12 pitch · 9/12 pitch → · All pitches in degrees

Frequently asked questions

How many degrees is a 8/12 roof pitch?

A 8/12 roof pitch is 33.69 degrees.

What is the multiplier for a 8/12 pitch?

The pitch multiplier for 8/12 is 1.2019. Multiply the footprint area or horizontal run by it to get the sloped area or rafter length.

Can you put shingles on a 8/12 roof?

Yes. 4/12 and steeper takes a standard shingle installation.

Is a 8/12 roof walkable?

With care. Many roofers use toe boards or roof jacks at this pitch.

Last reviewed 2026-10-10. Results are estimates for planning; confirm quantities with your supplier and requirements with your local building code and the manufacturer's instructions.