Roof Slope Calculator
Convert roof rise and run to slope percentage. Understand roof steepness for water drainage and structural design.
Formula & Explanation
Roof slope (or grade) expresses the steepness as a percentage. The formula is straightforward: Slope % = (Rise ÷ Run) × 100 For example, if a roof rises 6 feet over a 12-foot horizontal distance, the slope is (6 ÷ 12) × 100 = 50%. This calculator also displays the simplified pitch ratio (rise:run), which is more commonly used in roofing specifications.
Assumptions
- •Rise and run are measured in the same units (typically feet)
- •Rise must be non-negative; run must be positive
- •Slope represents roof steepness only; does not account for structural loads or local building codes
Example Calculation
A roof with 6 feet of rise over 12 feet of run has a slope of 50%, expressed as a 1:2 pitch.
Inputs
Results
Common Slope Percentages
| pitch | slope |
|---|---|
| 3:12 | 25.0% |
| 4:12 | 33.3% |
| 5:12 | 41.7% |
| 6:12 | 50.0% |
| 8:12 | 66.7% |
| 12:12 | 100.0% |
Frequently Asked Questions
Related Calculators
Roof Pitch Calculator
Calculate roof pitch, angle, and slope percentage from rise and run measurements.
Roof Angle Calculator
Calculate the roof angle in degrees and radians from rise and run measurements.
Roof Area Calculator
Calculate total roof surface area from building footprint and pitch. Essential for material estimation.
Roof Rise Calculator
Calculate vertical rise from roof angle and horizontal run. Essential for framing layout and structural planning.
Roof Run Calculator
Calculate horizontal run from roof angle and vertical rise. Use for framing calculations and structural planning.