The fastest way to mortise hinges or other metal hardware is to use a template with a router that has a guide bushing installed. But if you only have one or two to do, or they are an odd size, it makes more sense to just cut the mortises in by hand. In the time it would take to make the right size template, you could have the work done.

I show two common examples in this video, using just hand tools to layout and cut the mortises to the right depth:

The first step is to use the piece of hardware itself to mark the outline of the mortise, and I like to fasten it in place where it will be before doing that:

I used a single screw to hold the hinge in place while I used my homemade marking knife to mark around it. Note that when using the knife, I don’t go all the way to the corners, and that’s to avoid over-cutting.

To avoid chipping out the outside of the mortise when I use a knife to make the cuts deeper, I make these small relief cuts with a chisel: This is a good idea when you are using a router and template as well:

I prefer to use a sharp knife on the ends of a hinge mortise, but it can be done with a wide chisel as well:

I used my homemade carving knife to make the cut, but any sharp utility knife would work as well. I use a knife because it spreads the cut open less than driving in a chisel, and therefore the mortise doesn’t get bigger than it should be.

I draw a line on the outside of the edge of the mortise and use a sharp chisel to just score the line:

A knife can be used, but will tend to follow the grain, while a wide chisel will cut across it.

Next I make a series of cuts across the bed of the mortise only as deep as the thickness of the hinge leaf

I’ll often do this in two passes, with the second pass refining the cuts of the first pass.

Then the bulk of the chips can be carefully cut out and the bottom of the mortise cleaned up and fine tuned:

With practice, you can learn to do these quite quickly and always end up with a perfect fit for the hardware:

If you do cut too deep, you can always pack it out with pieces of cardboard.

For a closed mortise, here’s the procedure I follow: I start on the ends again, but use the chisel this time. You can see this better in the video above, but I make these cuts in a special way so as not to spread the wood at the ends of the mortise:

I can then remove the bulk of the wood at both ends using a smaller chisel:

And cleaning it out to the right depth and a snug fit: