Use this free app to calculate the run for any rafter in feet and inches, or just inches. Based on any roof pitch and any known rise.
The run is the horizontal distance a rafter travels. Learn how to perform this necessary task with ease and precision.
Install now:
iOS download
Android download
Calculate rafter run
Open app

Click on menu in the top left.
Select Rafter (known rise)

Click on Rafter (known rise) the fourth one down.
Rise

Enter the rise, then click equals.
Pitch

Enter how many inches per foot the rafter rises.
Rafter

Click equals one more time to cycle past this one.
Run

This is the horizontal distance the rafter travels.