The 6/12 pitch is one of the most common roof slopes in the US. It is steep enough to shed rain and snow, shallow enough to walk with care and uses standard shingles and underlayment. Here are the exact numbers and a full worked example.
6/12 roof pitch at a glance
| Measure | Value |
|---|---|
| Rise per foot of run | 6 inches |
| Angle | 26.57° |
| Slope | 50% |
| Area multiplier | 1.118 |
| Rafter length per foot of run | 13.42 inches |
The multiplier comes from √(1 + (6 ÷ 12)²) = √1.25 = 1.118. In plain words, every square foot of flat footprint becomes 1.118 sq ft of sloped roof.
Worked example: a 40 × 30 ft ranch house
The house is 40 ft long and 30 ft wide with a 12 inch overhang on every side and a simple gable roof.
- Footprint with overhang: (40 + 2) × (30 + 2) = 42 × 32 = 1,344 sq ft
- Roof area: 1,344 × 1.118 = 1,503 sq ft
- With 10% waste: 1,503 × 1.10 = 1,653 sq ft = 16.53 squares
- Shingle bundles: 16.53 × 3 = 49.6, so buy 50 bundles
- Synthetic underlayment: about 1,650 sq ft with overlaps, so 2 rolls of 10 squares
You can open this exact roof in the calculator: 40 × 30 house at 6/12. Change any number to match your house.
Rafter length
For the same house, the run of each rafter is half the width plus the overhang: 15 + 1 = 16 ft. Multiply by 1.118 to get 17.9 ft along the slope. Framers buy 18 ft stock and cut from there, before adding the ridge and plumb cut details.
6/12 compared with nearby pitches
Same 42 × 32 ft footprint, same overhang:
| Pitch | Angle | Roof area | Squares (10% waste) | Bundles |
|---|---|---|---|---|
| 4/12 | 18.43° | 1,417 sq ft | 15.58 | 47 |
| 5/12 | 22.62° | 1,456 sq ft | 16.02 | 49 |
| 6/12 | 26.57° | 1,503 sq ft | 16.53 | 50 |
| 7/12 | 30.26° | 1,556 sq ft | 17.12 | 52 |
| 8/12 | 33.69° | 1,615 sq ft | 17.77 | 54 |
| 12/12 | 45.00° | 1,901 sq ft | 20.91 | 63 |
Going from 6/12 to 8/12 adds about 112 sq ft of roof on this house, roughly 4 more bundles. Going down to 4/12 saves about 86 sq ft.
Pros and cons of a 6/12 roof
Pros
- Sheds water and light snow well, with fewer leak risks than low slopes
- Works with every common shingle type and standard underlayment
- Leaves usable attic space for storage and ventilation
- Most roofers can work it without special staging
Cons
- About 12% more roof area than the footprint, so more material than a 4/12 roof
- Still a steep roof for fall protection rules
- In very heavy snow regions, steeper pitches shed snow faster
How to confirm your roof is 6/12
Hold a level flat against the roof edge or a rafter, measure 12 inches along the level, then measure straight down (or up) to the roof. If that distance is 6 inches, you have a 6/12 roof. Our guide on how to measure roof pitch covers phone app and attic methods too, and the roof pitch angle chart converts any reading to degrees.