Roof Pitch Calculator
Determine roof pitch, angle and rafter length.
Determine your roof pitch, angle in degrees, and the rafter length multiplier from a simple rise-over-run measurement.
Measurement System
Your Estimate
Pitch
6/12
Angle
26.6°
Rafter Length Factor
1.118 ft per ft of run
Multiply the rafter length factor by your total run (in feet) to get rafter length. Standard run reference is 12 inches.
Results Actions
Accuracy & Assumptions
- Results are estimates only.
- Actual pitch and rafter length can vary with roof framing and structural details.
- Consider verifying measurements from multiple points on the roof.
- Verify all rise and run measurements on site before ordering trusses or materials.
- Check local building codes and manufacturer specifications for roofing at your pitch.
How This Calculator Works
- 1Measure the rise (vertical) over a 12" run using a level and tape measure.
- 2Enter the rise and run in inches — 12" run is the industry standard.
- 3We calculate the pitch ratio, the angle in degrees, and the rafter length factor.
Helpful Tips
- Multiply the rafter length factor by your horizontal run to get true rafter length.
- Steeper pitches shed water and snow faster but need more roofing material per square foot.
- Always verify pitch on-site before ordering trusses or roofing materials.
This calculator provides an estimate for planning purposes only. Material needs vary by site conditions, waste and supplier specifications — always confirm final quantities with your contractor or supplier before purchasing.