Roof Pitch Calculator
Calculate roof pitch, angle, and rafter length for your roofing project.
Roof Pitch Calculator
Calculate roof pitch, angle, and rafter length multiplier
Formula
Pitch = Rise ÷ Run × 12Expressed as X:12 ratio (rise per 12 inches of run)
How to Use This Calculator
- 1
Measure rise
Measure the vertical rise of your roof in inches.
- 2
Measure run
Measure the horizontal run (typically 12 inches for standard pitch notation).
- 3
Get results
See pitch ratio, angle in degrees, and rafter multiplier.
Frequently Asked Questions
What does 6/12 roof pitch mean?
A 6/12 pitch means the roof rises 6 inches for every 12 inches of horizontal run, or about 26.5 degrees.
What is a good roof pitch?
Most residential roofs are 4/12 to 9/12. Steeper pitches shed water better but cost more.
How do I use the rafter multiplier?
Multiply your horizontal run by the rafter multiplier to get the rafter length.