How it works
Angle=atan(rise/run); slope percent=rise/run×100; rise per 12 units=rise/run×12.
Input definitions
- Roof rise in any length unit
- Enter the value in the labeled unit.
- Horizontal run in the same unit
- Enter the value in the labeled unit.
A worked example
- Roof rise in any length unit
- 6
- Horizontal run in the same unit
- 12
Assumptions & limits
Geometric/material planning only. Use consistent labeled units and verify manufacturer instructions and site measurements. Does not determine structural suitability, legal compliance or installation safety.
Sources & review
Maintained by AnsRio. Methods and examples use automated checks; this does not imply independent professional certification.
Method updated 2026-10-17. Content checked against the stated method and examples. Our verification approach.
Common questions
Should I order exactly the quantity shown?
Treat the result as a planning estimate. Check measurements, units, pack sizes, waste, openings and local requirements; the stated formula does not replace a project-specific design.
How does the Roof pitch and slope angle tool work?
Angle=atan(rise/run); slope percent=rise/run×100; rise per 12 units=rise/run×12.
What are the assumptions and limits of Roof pitch and slope angle?
Geometric/material planning only. Use consistent labeled units and verify manufacturer instructions and site measurements. Does not determine structural suitability, legal compliance or installation safety.