How to read the roof pitch chart
The table below lists every whole-inch roof pitch from 1/12 up to 24/12, with run held fixed at 12 (the industry-standard denominator). Each row is generated at build time from three formulas applied to that rise-and-run pair, so the same math you can run on a calculator by hand is what produced every cell. Pitch is the rise-over-run ratio written as a fraction of 12, angle is that ratio converted to degrees, slope factor is the multiplier from flat area to sloped roof area, and grade is the same ratio expressed as a percentage instead of a fraction.
Use the filter box above the table to jump straight to a pitch. Typing a number matches any pitch whose rise starts with those digits, so typing 6 surfaces 6/12 (and 6/12 alone, since no other rise between 1 and 24 starts with a lone 6 followed by nothing). Typing 1 surfaces 1/12 plus every pitch from 10/12 through 19/12, since those risers all start with the digit 1.
What slope factor actually is, and why it is the useful number
A flat ceiling plane and the roof plane above it cover the same horizontal footprint, but the roof plane is longer because it is tilted. Slope factor is exactly that ratio: the length of the sloped surface divided by the length of the flat run underneath it, which by the Pythagorean theorem is the square root of rise squared plus run squared, divided by run. Multiply a building's flat footprint area by the slope factor for its pitch and the result is the true sloped roof area, which is the number that actually determines how many bundles of shingles, how many rolls of underlayment, and how many sheets of decking a job needs. Estimating material off the footprint alone instead of the slope-corrected area is a common source of running short mid-job, and the error grows fast as pitch increases; at 4/12 the correction is only about 5%, but by 12/12 it is a full 41%, and by 24/12 it is well over double the flat area.
Measuring pitch on site with a level and a tape
You do not need to climb onto a roof surface to find its pitch. Hold a torpedo level (or any straight edge) horizontal against the underside of a rafter, ideally from inside the attic where it is safer and the framing is exposed. Extend the level out exactly 12 inches from a fixed point, keeping it level, then measure straight down from the 12 inch mark to the rafter's bottom edge with a tape measure. That vertical distance in inches is the rise, and the pitch is that number over 12. A 5 inch gap at the 12 inch mark is a 5/12 pitch. The same technique works from outside using a rafter square (a speed square) hooked over the fascia or a rake edge, reading the pitch directly off the square's built-in degree and pitch scale.
Where each column gets used on a real job
The pitch fraction itself (4/12, 6/12, and so on) is the number contractors, inspectors, and manufacturer spec sheets all reference, since it is the plain-language way pitch gets communicated on a job site or a permit. Angle in degrees matters for framing calculations, rafter cut angles, and anywhere a saw or a speed square needs a degree setting rather than a ratio. Slope factor is the material takeoff number, converting footprint or attic-floor area into actual roof area for shingles, underlayment, decking, and paint or coating coverage. Grade percentage shows up in civil and drainage contexts and on some manufacturer minimum-slope specifications, since it expresses the same ratio in the percent format those documents use.
Common pitches and what they signal
Pitches from about 2/12 to 4/12 are considered low-slope; many asphalt shingle products set a minimum installable pitch in this range and below it you typically need a membrane or low-slope roofing system instead. From roughly 4/12 to 9/12 covers most standard residential roofs, walkable with reasonable care and compatible with the widest range of roofing materials. Above about 9/12 to 12/12 pitches are steep-slope, usually requiring roof jacks, staging, or fall protection to work on safely, and they show up on traditional or high-style architectural roofs. Beyond 12/12 pitches are unusual outside of specific architectural styles (like steep Gothic or A-frame designs) and involve specialty framing and access considerations well past what this chart covers.