Roof Pitch Calculator and Chart
Find your roof pitch from rise and run
Enter the vertical rise and horizontal run for the same roof slope. You get the pitch per 12, the angle, the slope percentage and a diagram, and you can print or save the result as a PDF. Already know the pitch or angle? Use the converter.
The calculator is loading. If it does not appear, please refresh the page or call us at 770-406-6646.
Understanding rise and run
Roof pitch describes a roof’s steepness using vertical rise and horizontal run. It is written as inches of rise for every 12 inches of horizontal run.
Rise vs. run
Rise is the vertical change between two points on a roof slope. Run is the horizontal distance between the same points, not the distance along the sloping surface.
For a symmetrical gable measured from eave level to ridge, run is half the full span. Do not halve a measurement that is already the run.
Use measurements from plans or a qualified professional. Do not climb onto a roof to measure.
Reading a pitch ratio
A 4:12 pitch rises 4 inches for every 12 inches of horizontal run. The same proportion applies at any scale.
- 3:12 — about 14.04°
- 6:12 — about 26.57°
- 12:12 — equal rise and run, 45°
These are examples, not recommendations for a particular roof or roofing material.
How the calculation works
- Pitch per 12 = rise ÷ run × 12
- Slope percentage = rise ÷ run × 100
- Angle = arctangent of rise ÷ run, in degrees
Example: 4 feet of rise over 8 feet of run gives a 6:12 pitch, 50% slope and an angle of about 26.57°.
Using your result
Use the pitch to describe your roof and compare it with product specifications. A non-whole-number pitch should not automatically be rounded up to select a bracket.
Confirm the actual pitch and fitting requirements before ordering. The result does not establish structural safety, roofing suitability, drainage performance or snow-load capacity. Sloping length is the straight-line distance between the measured points, not a rafter cut length.
Roof pitch chart
