Roof Pitch, Angle and Slope Factor Calculator
Convert roof rise and horizontal run into angle, percentage slope and roof area multiplication factor.
Formula
Planning estimate. Check product specifications and local requirements before purchasing.
Worked example: Roof Pitch Calculator
Measurements in this example
| Roof rise | 40 cm |
|---|---|
| Roof run | 100 cm |
Calculated quantities
| Roof angle | 21.8° |
|---|---|
| Slope | 40% |
| Slope factor | 1.077 |
What to check
This calculation uses: Roof rise, Roof run. It returns: Roof angle, Slope, Slope factor.
Measure horizontal run and vertical rise from the same reference points. Do not substitute the sloping surface for horizontal run.
Verify the roof structure, loads and cutting layout with a qualified designer before altering or fabricating structural members.
Use the units beside each field. The values in the worked example are starting inputs; replace them with your measurements and the specifications of your material.
Compare alternatives
Open a tool, enter your measured dimensions, then save an estimate. Keep another version if you want to compare products or allowances.