Professional Roof Pitch Calculator
Calculate pitch, angle, and grade for your roofing project
Inches
Feet
Meters
Centimeters
Roof Specifications:
Roof Pitch Ratio
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Angle (Degrees)
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Grade Percentage
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Pitch Factor
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Understanding Roof Pitch
Roof pitch is a numerical measure of the steepness of a roof. In construction, it is most commonly expressed as a ratio of the Rise (vertical height) over the Run (horizontal distance). In the United States, this is typically standardized to a ratio over 12 inches.
How the Calculation Works
The math behind roof pitch involves basic trigonometry:
- Pitch Ratio: Calculated as (Rise / Run) * 12. For example, a 6-inch rise over a 12-inch run is a "6:12 pitch".
- Angle: Calculated using the arctangent function:
arctan(rise / run). - Grade: Expressed as a percentage:
(rise / run) * 100.
Common Pitch Classifications
| Type | Ratio | Angle |
|---|---|---|
| Flat Roof | 0/12 to 2/12 | 0° – 9.5° |
| Low Slope | 2/12 to 4/12 | 9.5° – 18.4° |
| Conventional | 4/12 to 9/12 | 18.4° – 36.9° |
| Steep Slope | Above 9/12 | > 36.9° |
Why Pitch Matters for Your Home
The pitch determines which materials can be used. For instance, asphalt shingles are generally not recommended for pitches below 2/12, as water can seep under the shingles. Conversely, very steep roofs (over 12:12) require specialized safety equipment and installation techniques, increasing labor costs.