Rafter Line Length Calculator

rafter line length pic
Deduct half the thickness of the ridge from the span length this length
is the correct measurement from the top plumb line to the birdsmouth plumb line.

To get overall plumb to plumb length add overhang horizontal length to horizontal span
(less subfascia and fascia thickness)

Horizontal Span of Rafter (inches,run)
Roof Pitch (inches rise, e.g. 6/12)
Hip or Valley Thickness
Center to Center Rafter Spacing (inches)
Rafter Thickness
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 =


hipjack valleyjack