Convert between roof pitch ratio, degrees, and percentage. Enter rise and run to calculate pitch in all common formats.
Roof pitch describes the steepness of a roof and is expressed in several ways: as a ratio (rise:run), in degrees, or as a percentage. Converting between these formats is a common task for roofers, framers, architects, and homeowners evaluating roofing options.
This rafter pitch calculator lets you enter the rise and run of your roof in any units and instantly converts to all three pitch expressions. It also tells you whether the pitch qualifies for various roofing materials—some shingles require a minimum 4:12 pitch, while metal roofing can go as low as 1:12.
Understanding pitch is crucial for material selection, drainage, snow load, aesthetics, and walkability. A 4:12 roof is walkable for most people, while anything above 8:12 typically requires roof brackets or scaffolding for safe work.
By quantifying this parameter precisely, construction teams can optimize material orders, reduce on-site waste, and ensure structural requirements are met safely and efficiently.
Pitch is expressed differently by roofers (rise:12), engineers (degrees), and grading contractors (percentage). This calculator bridges all three formats instantly so everyone's on the same page, and it flags material compatibility. Having precise numbers at hand streamlines project planning discussions with clients, architects, and subcontractors, building trust and reducing costly misunderstandings on the job.
Pitch Ratio = Rise / Run × 12 (expressed as X:12) Angle (degrees) = arctan(Rise / Run) × 180 / π Slope % = (Rise / Run) × 100
Result: 6:12 pitch = 26.57° = 50.0%
A rise of 6 over a run of 12 gives a 6:12 pitch. The angle is arctan(6/12) = 26.57 degrees. As a percentage, 6/12 × 100 = 50%. This is a medium pitch suitable for most roofing materials.
While often used interchangeably, these terms have distinct meanings. Pitch was historically the ratio of rise to full span (not run). Modern usage equates pitch with slope as rise per 12 inches of run. Grade is the slope expressed as a percentage and is more common in road and site work than roofing.
Steeper roofs shed snow more effectively, reducing snow accumulation loads. Building codes in heavy snow regions may require steeper minimum pitches or increased structural capacity for low-slope roofs. A roof steeper than about 70° (roughly 28:12) sheds snow almost immediately.
Higher pitches create more usable attic space. A 12:12 pitch creates a 45° attic that can be finished as living space, while a 4:12 pitch provides only a cramped crawl space for storage and mechanical equipment.
A 4:12 pitch equals arctan(4/12) = 18.43 degrees. This is considered a moderate slope and is the minimum pitch for most asphalt shingle installations.
A truly flat roof has 0:12 pitch (0°), but in practice flat roofs have a slight slope of 1/4″ per foot (about 0.25:12 or 1.2°) for drainage.
Residential roofs rarely exceed 12:12 (45°). Steep pitches like 16:12 or 18:12 are found on mansard roofs, church steeples, and A-frame cabins.
From the attic, hold a level against a rafter, measure 12 inches along the level, then measure the vertical distance from the level to the rafter. That vertical distance is your pitch per 12 inches of run.
Yes. Asphalt shingles: 4:12 minimum. Metal panels: 3:12 minimum (some at 1:12). Built-up/membrane: any low slope. Clay/concrete tile: 4:12 minimum. Wood shakes: 4:12 minimum. Always check manufacturer requirements.
The most common residential pitches are between 4:12 and 8:12, with 5:12 and 6:12 being especially popular. These provide good drainage, walkability, and aesthetic proportions.