Find your roof pitch from a simple rise-and-run measurement — instantly get the pitch ratio (X:12), angle in degrees, grade percentage and slope factor.
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Enter your roof’s rise and run to find its pitch.
Roof pitch is how steep your roof is, written as a ratio of vertical rise to horizontal run — almost always over a standard 12-inch run. A “6:12” pitch means the roof rises 6 inches for every 12 inches it travels horizontally. The larger the first number, the steeper the roof.
Pitch drives nearly every other roofing decision: which materials you can use, how much surface area you actually have to cover, how well the roof drains, and how difficult (and costly) it is to install. Steeper roofs need more material and more labor.
Common roof pitches converted to angle, percentage grade and the slope factor used to turn a footprint into roof area.
| Pitch (rise:run) | Angle | Grade | Slope factor | Category |
|---|---|---|---|---|
| 1:12 | 4.8° | 8% | 1.003 | Low-slope |
| 2:12 | 9.5° | 17% | 1.014 | Low-slope |
| 3:12 | 14.0° | 25% | 1.031 | Conventional |
| 4:12 | 18.4° | 33% | 1.054 | Conventional |
| 5:12 | 22.6° | 42% | 1.083 | Conventional |
| 6:12 | 26.6° | 50% | 1.118 | Conventional |
| 7:12 | 30.3° | 58% | 1.158 | Conventional |
| 8:12 | 33.7° | 67% | 1.202 | Conventional |
| 9:12 | 36.9° | 75% | 1.250 | Conventional |
| 10:12 | 39.8° | 83% | 1.302 | Steep |
| 12:12 | 45.0° | 100% | 1.414 | Steep |
Use a 12-inch level and a tape measure. You can measure on the roof, or on a rafter from inside the attic — no ladder needed.
Hold the level perfectly horizontal against the roof or rafter and mark the 12-inch point. That distance is your run.
From that 12-inch mark, measure straight up to the roof surface. That vertical distance is your rise. Enter rise and run above for your exact pitch.
Most residential roofs fall between 4:12 and 9:12 — steep enough to shed water and use shingles without extreme labor costs. Below 2:12 is low-slope or flat and needs membrane roofing (TPO, EPDM, PVC); above 9:12 is steep-slope and adds labor.
Measure from inside the attic: hold a 12-inch level horizontally against the underside of a rafter, then measure straight up from the 12-inch mark to the rafter. That rise over the 12-inch run is your pitch.
They describe the same steepness. Pitch is usually written as a ratio (6:12), while slope is often given as an angle in degrees or a percentage grade. The Roof Slope Calculator converts between them.
The slope factor is a multiplier that converts your flat footprint into the actual sloped roof area. A 6:12 roof has a factor of about 1.118, so its surface is ~12% larger than the ground it covers. Apply it with the Roof Area Calculator.
Once you have your numbers, compare free quotes from up to 3 licensed local roofers. No pressure — the choice is yours.