Cutting rafters is straightforward once you have the run and the pitch — pick a pattern stick, lay out the cuts with a framing square, cut, and test-fit before cutting the rest. This guide walks through how to cut roof rafters step by step, the same procedure that answers "making rafters" or "rafter cutting" questions, and covers all the standard rafter cuts (plumb, seat, heel, tail) in one workflow.
How to measure and cut roof rafters reduces to a six-step procedure that experienced framers use on every job. The procedure also tells you how to lay out rafters from scratch, how to measure and cut rafters of any size, and what to inspect when you test-fit before production cutting. Roof rafter cuts are the same regardless of building size — once you know the pitch and run, the cut angles are determined and you only need to scale the rafter length.
Step 1 — Get your measurements
You need three numbers: the run (half the building span), the pitch (rise per 12 inches of run), and the overhang you want past the wall plate.
For a 24-foot-wide building with a 6/12 pitch and a 16-inch overhang, run is 12 feet, pitch is 6/12, and overhang is 16 inches. Plug into the calculator above for total rafter length.
Step 2 — Lay out the pattern rafter
Pick the straightest, cleanest stick of lumber for your pattern. Lay it crown-up on a pair of sawhorses, top edge facing you.
Set your framing square with the rise on the tongue (short leg) and 12 on the blade (long leg). For 6/12, that's 6 on the tongue and 12 on the blade.
Mark the plumb cut on one end. Step the square along the rafter, advancing 12 inches per step, for as many steps as your run requires (12 steps for a 12-foot run). Mark the heel of each step.
At the wall-plate end, lay out the bird's mouth — typically a 3.5-inch deep seat (matching a 2x4 plate) with a plumb heel cut.
Below the bird's mouth, continue stepping at the same pitch for your overhang.
Step 3 — Cut and test-fit
Cut the pattern rafter with a circular saw. Use a framing speed square as a saw guide for the angled cuts.
Test-fit the pattern rafter on the actual building before cutting any others. The seat should sit flush on the plate; the plumb cut should meet the ridge cleanly. If anything is off, adjust before cutting more lumber.
Once the pattern fits, use it as a template to mark and cut the remaining rafters.
Need to run the numbers?Use the free roof pitch calculator on the home page to convert pitch to angle, calculate rafter length, or estimate roof area in any unit.