RendervisRoof Pitch Calculator
Calculate roof slope angle, percentage, ratio, and rafter length from rise and run measurements.
Vertical height from the eave to the ridge.
Horizontal distance from the eave to directly below the ridge.
Roof pitch
Pitch diagram
Understanding Roof Pitch
Roof pitch describes the steepness of a roof. It is defined by the relationship between the vertical rise and the horizontal run. A steeper pitch sheds water and snow more effectively.
Pitch Formula
Angle = arctan(Rise ÷ Run)
Slope % = (Rise ÷ Run) × 100
Rafter length = √(Rise² + Run²)
Example
A roof with a 300 cm rise and 600 cm run has a pitch of 26.6°, a 50% slope, and a rafter length of approximately 671 cm.
Frequently Asked Questions
- What is a good roof pitch?
- It depends on climate and materials. A 30°–45° pitch is common for residential buildings. Steeper pitches shed rain and snow better; flatter pitches are more economical.
- How is roof pitch expressed?
- Roof pitch can be expressed as an angle in degrees, a percentage slope, or a ratio (e.g., 6:12, meaning 6 inches of rise for every 12 inches of run).
- What is the minimum roof pitch for tiles?
- Most clay and concrete roof tiles require a minimum pitch of about 22° (roughly 40% slope). Always check the specific tile manufacturer's recommendations.
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