Roof Pitch Calculator
Calculate roof pitch, angle, and slope percentage from rise and run measurements.
Formula & Explanation
**Roof pitch** is the ratio of vertical rise to horizontal run, representing the steepness of your roof. The most common way to express roof pitch is as a ratio like 6:12 (six inches of rise for every twelve inches of run). This is crucial for structural integrity, drainage, material selection, and safety considerations in construction. **Conversion formulas:** - Pitch Ratio = Rise : Run (typically normalized to :12) - Angle (degrees) = arctan(rise ÷ run) × 180/π - Slope Percentage = (rise ÷ run) × 100 For example, a 6:12 pitch means 6 inches of vertical rise per 12 inches of horizontal run, which converts to approximately 26.57 degrees or 50% slope. Understanding these relationships is essential for roofing material selection, labor estimation, and building code compliance.
Assumptions
- •Measurements should be from the same reference plane (ridge to eave)
- •Rise and run must both be positive values greater than zero
- •Typically, the run is standardized to 12 inches (1 foot) for pitch notation in North America
- •Pitch calculation assumes a straight linear slope without consideration of curved or complex roof shapes
- •Results are mathematical conversions and should be verified with actual measurements for construction planning
- •Building codes may have minimum pitch requirements based on roofing material and local climate
- •Steeper pitches provide better water drainage but require additional labor and safety precautions
Example Calculation
A 6:12 pitch (read as "six to twelve") means 6 inches of vertical rise for every 12 inches of horizontal run.
Inputs
Results
Common Roof Pitches
| pitch | angle | percentage |
|---|---|---|
| 3:12 | 14.04° | 25.0% |
| 4:12 | 18.43° | 33.3% |
| 5:12 | 22.62° | 41.7% |
| 6:12 | 26.57° | 50.0% |
| 8:12 | 33.69° | 66.7% |
| 10:12 | 40.05° | 83.3% |
| 12:12 | 45.00° | 100.0% |
Frequently Asked Questions
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