Rafter Length Calculator
Calculate the exact rafter length for your roofing project. Determine dimensions based on roof pitch, span, and overhang for accurate construction planning.
Step 1: Roof Dimensions
Understanding Roof Pitch
Roof pitch is expressed as a ratio of vertical rise to horizontal run (e.g., 6/12 means 6 inches of rise for every 12 inches of run). Common residential pitches range from 4/12 to 9/12.
Step 2: Advanced Settings
About Rafter Calculations
Rafter length is calculated using the Pythagorean theorem. Overhang and birdsmouth cuts are added to the theoretical length. Proper calculations ensure structural integrity and material efficiency.
Rafter Calculation Results
Total Rafter Length
Roof Pitch Comparison
| Pitch Ratio | Angle | Rafter Length | Rise per 12″ run |
|---|
Detailed Rafter Dimensions
Rafter Length Formula
Rafter Length = √(Run² + Rise²) + Overhang
To calculate rafter length: Square the run and rise, add them together, take the square root, then add the overhang length. For pitch ratios, rise = (pitch/12) × run.
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