Roof Pitch Calculator
Convert any roof pitch between rise/run notation, degrees, and percentage slope. See the pitch factor used to calculate true roof area.
Enter Pitch
Formulas used
Pitch notation
Pitch = rise / 12 Expressed as X/12 where X is the rise in inches for every 12 inches of horizontal run.
Degrees
Degrees = arctan(rise ÷ 12) × (180 ÷ π) Converts the slope ratio to an angle using the inverse tangent function.
Percentage slope
% Slope = (rise ÷ 12) × 100 Used in commercial roofing and civil engineering. A 6/12 pitch = 50% slope.
Pitch factor (area multiplier)
Pitch factor = √(1 + (rise ÷ 12)²) Multiply your footprint area by this number to get the true sloped roof area.
Common Roof Pitches — Full Reference
| Pitch | Degrees | % Slope | Pitch Factor | Walkable | Typical Use |
|---|---|---|---|---|---|
| 1/12 | 4.8° | 8% | 1.0035 | Yes | Low-slope / flat-roof transition |
| 2/12 | 9.5° | 17% | 1.0138 | Yes | Low-slope, requires special shingles |
| 3/12 | 14.0° | 25% | 1.0308 | Yes | Ranch-style, carports |
| 4/12 | 18.4° | 33% | 1.0541 | Yes | Common suburban residential |
| 5/12 | 22.6° | 42% | 1.0833 | Yes | Common residential |
| 6/12 | 26.6° | 50% | 1.1180 | Yes | Cape Cod, cottages |
| 7/12 | 30.3° | 58% | 1.1577 | Caution | Traditional colonial |
| 8/12 | 33.7° | 67% | 1.2019 | Caution | Tudor, steep colonial |
| 9/12 | 36.9° | 75% | 1.2500 | No | Victorian |
| 10/12 | 39.8° | 83% | 1.3017 | No | A-frame, chalet |
| 12/12 | 45.0° | 100% | 1.4142 | No | A-frame, steep chalet |
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Frequently Asked Questions
Roof pitch is the steepness of a roof expressed as a ratio of vertical rise to horizontal run. A 4/12 pitch means the roof rises 4 inches for every 12 inches of horizontal distance.
From the ground, hold a level horizontally against the roof edge (or at the eave) and measure 12 inches along it. Then measure straight down from the 12-inch mark to the roof surface — that vertical measurement is your rise. The pitch is rise/12.
Pitches up to 6/12 are generally considered walkable for experienced roofers with proper footwear. Pitches of 7/12 and above typically require safety equipment and scaffolding. Always use appropriate fall protection.
Most American residential roofs range from 4/12 to 6/12, which provides good water runoff while remaining easy to work on. Low-slope roofs (under 2/12) require special low-slope or flat-roof materials.
Degrees = arctan(rise ÷ 12). For example, a 6/12 pitch: arctan(6/12) = arctan(0.5) ≈ 26.57°. This calculator does the conversion automatically for all common pitches.