Rafter Calculator

Common rafter length, cut angles and count for a gable roof. (Sizing comes from span tables — not included.) Free, no sign-up.

Rafter length is measured along the top edge from the ridge plumb cut to the tail, after taking half the ridge board off the run. Plumb cuts are set at the roof angle; the seat cut is square to it.

This doesn't size rafters — check the NBC span tables or a designer for size and spacing.

Taulien Construction · Fredericton, New Brunswick · info@taulien.com · 506-230-5131