Roof Run Calculator
Calculate horizontal run from roof angle and vertical rise. Use for framing calculations and structural planning.
Formula & Explanation
The run is calculated from angle and rise using the cotangent function: Run = Rise ÷ tan(Angle) Where angle is in degrees and converted to radians. For example, with a 26.57° angle and 6-foot rise: Run = 6 ÷ tan(26.57°) = 6 ÷ 0.5 = 12 feet This produces a 6:12 pitch. This calculator is complementary to the roof rise calculator and is useful when you know the desired vertical rise but need to determine the horizontal distance for layout purposes.
Assumptions
- •Angle must be greater than 0 and less than 90 degrees
- •Rise and run are measured in the same units (typically feet)
- •Calculation assumes a level building base
Example Calculation
A 26.57-degree roof angle with 6 feet of vertical rise requires 12 feet of horizontal run, creating a 6:12 pitch.
Inputs
Results
Run by Angle and Rise
| angle | rise | run |
|---|---|---|
| 14.04° | 3 ft | 12.0 ft |
| 18.43° | 4 ft | 12.0 ft |
| 22.62° | 5 ft | 12.0 ft |
| 26.57° | 6 ft | 12.0 ft |
| 33.69° | 8 ft | 12.0 ft |
| 45.00° | 12 ft | 12.0 ft |
Frequently Asked Questions
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