The one rule: mortise depth equals the hinge leaf thickness, so the leaf sits flush with the wood. Too shallow and the door binds and won't close; too deep and you get a gap that strains screws.
By hand with a chisel
Trace the leaf
Position the leaf, knife around it, and set a depth line equal to the leaf thickness on the door edge.
Score the perimeter
Tap the chisel straight down along your outline, bevel facing in, to the depth line.
Relief cuts
Make a series of shallow chisel cuts across the recess every 1/8–1/4″ at the mortise depth.
Pare flat
Hold the chisel bevel-down and pare out the chips, then flatten the floor. Test-fit the leaf flush.
With a router and jig
For more than a couple of doors, a hinge-mortising template plus a router with a guide bushing cuts identical, perfectly flat mortises in seconds. Square the rounded router corners with a chisel if your hinges have square corners.
Tools for a clean mortise
- A sharp chisel sized near the hinge width, or a router with a hinge-mortise jig
- A utility knife and a pencil
- A combination square
- The hinge itself, as your template
Chisel or router?
For one or two doors, a sharp chisel is faster to set up and plenty accurate. For a whole house of doors, a router and hinge jig pays off in speed and consistency. Either way the goal is identical: a flat recess exactly the thickness of the hinge leaf so it sits dead flush with the wood.
Setting the depth
Depth is the whole game. Too deep and the door binds against the jamb and won't latch; too shallow and it springs open (hinge-bound). Score the outline with a knife, make a grid of shallow chisel cuts inside it, then pare the waste out to the scored depth line. Test-fit the leaf often — it should sit flush, with the screw holes centered.
Common mistakes
- Cutting to the pencil line instead of the knife line, leaving the recess oversized.
- Going past the leaf thickness — you can't easily add wood back.
- Forgetting to line the barrel/knuckle so it clears the door edge and the door can swing fully.
Frequently asked questions
How deep should a hinge mortise be?
Exactly the thickness of the hinge leaf so it sits flush. That's usually about 1/8″ for residential hinges, but measure your actual leaf.
Router or chisel?
Chisel for one or two doors; a router and jig for a whole house of doors where consistency and speed pay off.