How roof pitch is calculated
Roof pitch compares vertical rise with horizontal run. To express any rise-and-run measurement as the common X:12 format, divide rise by run and multiply by 12.
Roof pitch example
A roof that rises 6 inches over a 12-inch horizontal run has a 6:12 pitch. Its roof angle is approximately 26.57 degrees.
Pitch, angle and slope percentage
These values describe the same roof slope in different ways. Pitch is commonly used in roofing, degrees describe the angle, and slope percentage expresses rise as a percentage of run.
Rise and run must use the same unit. Inches, centimeters or feet all work as long as both values use the same unit.
Frequently asked questions
What angle is a 6:12 roof pitch?
Approximately 26.57 degrees.
What does 4:12 roof pitch mean?
The roof rises 4 units vertically for every 12 units of horizontal run.
Is roof pitch the same as roof slope?
They describe the same incline, but pitch notation, angle and percentage express it differently.
Can I enter a run other than 12?
Yes. The calculator converts your rise and run to the equivalent X:12 pitch.
Using this calculator effectively
Roof pitch describes the vertical rise for a given horizontal run. This calculator converts rise and run into pitch, angle, slope percentage and a slope factor so the same roof geometry can be understood in several common formats.
Common uses
- Converting measured rise and run into an X-in-12 roof pitch.
- Finding roof angle in degrees for layout or comparison.
- Obtaining a slope factor for roof-area calculations.
Tips for a better estimate
- Measure rise and run over the same reference section of roof.
- Keep units consistent because the ratio matters more than the chosen unit.
- Do not use pitch alone to determine structural suitability or code compliance.
Helpful guides
Related calculations
Roof Slope Calculator · Roof Square Footage Calculator · Roof Shingle Calculator