Rafter Length Calculator
Common rafter length, total rise and roof angle from run and pitch, with eave overhang length and tail drop. Includes a diagram.
- Rafter length from horizontal run and pitch
- Total rise and roof angle
- Overhang length along the slope and drop below the plate
- Rafter diagram
How to use
- Enter the run: the horizontal distance from the outside of the wall to the center of the ridge, which is half the building span for a common rafter.
- Enter the pitch as rise per 12 of run (6 for a 6/12 roof).
- Enter the overhang as its horizontal projection beyond the wall.
- Read the rafter length to the ridge, the length including the overhang, the total rise, the roof angle and how far the tail drops below the plate.
- Lengths are theoretical line lengths; the tool does not deduct the ridge board thickness.
- Length fields accept the same entries as the Feet and Inches Calculator: 9' 6, 7 3/4", 2743mm or 3m + 6'. A plain number means inches, or millimeters when the Units panel is set to metric.
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