Rafter Line Length Calculator
Deduct half the thickness of the ridge
from the span length
is the correct measurement from the top plumb line to the birdsmouth plumb line.
To get overall plumb to plumb length
overhang horizontal length
(less subfascia and fascia thickness)
Horizontal Span of Rafter (inches,run)
Roof Pitch (inches rise, e.g.
Hip or Valley Thickness
Center to Center Rafter Spacing (inches)
Common Plumb to Plumb Line Length (inches) =
Common Line Length Ratio =
Hip/Valley Line Length (inches) =
Hip/Valley Line Length Ratio =
Jack Step Down Each Rafter =