Span64

Web calculator

Rafter calculator

Give the pitch as rise per 12″ of run and the run itself. The estimate returns the common rafter line length, the rise and the plumb cut angle.

Pitch

A 6/12 roof rises 6″ over every 12″ of run.

Run (outside of wall to ridge center)

Estimate · rounded to 1/16″

15′ 7 13/16″ common rafter

Common rafter length
15′ 7 13/16″Line length, before ridge and tail allowances.
Rise
7′ 0″
Plumb cut angle
26.57°Roof angle from horizontal, marked as the plumb cut.
Exact to 1/64″ in the app

Web estimates round lengths to 1/16″. Nothing you type is stored or sent anywhere. Span64 works to an exact 1/64″ on iPhone, iPad and Android.