Roof Run Calculator
Calculate roof run, pitch, rafter length, and roofing measurements for construction and renovation projects.
Step 1: Roof Dimensions
Roof Pitch Formula
Pitch = Rise ÷ Run (expressed as X:12)
Rafter Length = √(Run² + Rise²)
Angle = arctan(Rise ÷ Run)
Step 2: Calculation Options
Common Roof Pitches
Flat: 0:12 to 2:12
Low Slope: 2:12 to 4:12
Conventional: 4:12 to 9:12
Steep: 9:12 to 12:12+
Mansard: Varies, often steeper
Roof Calculation Results
Roof Pitch
Roof Type Comparison
| Roof Type | Typical Pitch | Rafter Length | Common Use |
|---|
Roof Calculation Formulas
Pitch = Rise ÷ Run (expressed as X:12)
Where:
• Rise = Vertical height (feet)
• Run = Horizontal distance (feet)
• Pitch is expressed as inches of rise per 12 inches of run
Other Calculations:
• Rafter Length = √(Run² + Rise²)
• Angle = arctan(Rise ÷ Run) in degrees
• Roof Area = Rafter Length × Building Width
Example Calculation
Example: 6:12 Pitch Roof
Run: 12 feet
Rise: 6 feet
Pitch: 6:12 (6 inches of rise per 12 inches of run)
Calculation:
Rafter Length = √(12² + 6²) = √(144 + 36) = √180 = 13.42 feet
Angle = arctan(6 ÷ 12) = arctan(0.5) = 26.6°
For a 20 ft wide building:
Roof Area (one side) = 13.42 × 20 = 268.4 sq ft
Total Roof Area (both sides) = 536.8 sq ft
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