Roof pitch is the steepness of a roof expressed as a ratio of vertical rise to horizontal run — for example, 6:12 means 6 inches of rise per 12 inches of horizontal run.
Common Roof Pitches
- Low slope (2:12 to 4:12): Requires special roofing materials, more prone to leaks
- Standard (4:12 to 9:12): Most residential homes, works with all shingle types
- Steep (9:12 to 12:12): Better drainage, more attic space, higher material and labor costs
- Very steep (12:12+): 45° or greater, requires special safety equipment for installation
Why Pitch Matters
Pitch affects material needs (steeper = more roofing area), drainage capacity, snow load handling, and aesthetic appearance. It also determines which roofing materials can be used — asphalt shingles require at least a 2:12 pitch.
Real-World Example
A home with a 30' × 40' footprint and 6:12 pitch. The pitch multiplier for 6:12 is 1.118. Roof area = 30 × 40 × 1.118 = 1,342 sq ft per side, or 2,684 sq ft total (both sides). That is about 27 roofing squares (1 square = 100 sq ft).
Frequently Asked Questions
How do I measure roof pitch?
Place a level horizontally against the roof rafters or surface. Mark 12 inches along the level. Measure the vertical distance from the end of the 12-inch mark down to the roof surface. That measurement in inches is your pitch (e.g., 6 inches = 6:12 pitch).
What is the best roof pitch for snow?
A pitch of 6:12 or steeper allows snow to slide off naturally. Lower pitches may require additional structural support for snow loads. In heavy snow regions, metal roofing on steep pitches (8:12+) sheds snow most effectively.
How do I convert roof pitch to degrees?
Divide rise by run, then take the arctangent. For 6:12: arctan(6/12) = 26.57°. Common conversions: 4:12 = 18.4°, 6:12 = 26.6°, 8:12 = 33.7°, 12:12 = 45°.