MIMF

so its my first build and so far only a couple hands full of mistakes lol. but nothing i couldn't redo or fix. But now I am at the stage to route out the neck pocket. I have a plan for a jig off the internet which i think will work well. My problem is I don't know how to figure out the depth of the pocket. I know this is very important and i really don't want to ruin all the work i have done so far. can anyone tell me if there is some sort of formula to use or what to measure to find the right depth? any help would be much appreciated

So, you're building a solid-body guitar? And is the neck pocket angled, or not? At any rate, I use a straightedge laid down the fingerboard so I can measure the height above the body at the bridge position. Whatever type of bridge you'll be using will tell you how high off the body that measurement needs to be.

yes its a solid body. bolt on neck. the heal of the neck is flat for now. and i i was thinking of doing a flat neck pocket as well and if worse came to worse use a shim. I understand that i have to measure the bridge. what i dont understand is what i watched on a video. he said that on a setup he liked the low E string had 1mm of clearance at the 12th fret which meant 2mm at the bridge. so he added bridge height + 2mm - the width of the heal and got the depth his pocket had to be. what i dont understand is where he got the 2mm at the bridge. Is it always just going to be double the width at the bridge of what you want your clearance to be at the 12th fret or is there someway to figure this out.

sorry didnt say the formula right. heal height-(2mm+bridge height ) = neck depth

Fender-type guitars or guitars using Fender-type bridges normally require a neck pocket that is 9/16" - 5/8" deep. I normally use a depth of 9/16" because this allows for a slightly lower action adjustment. These measurements, though, are contingent upon the neck thickness being 3/4" at the heel with a fretboard thickness of 1/4" for a total thickness or height of 1". For guitars using bridges that require a back angled neck, I like for the entire heel to be recessed into the body so that the fretboard extension has no gap under it. Therefore, I use a depth of 3/4" at the very heel end of the cavity and compensate by calculating and using the correct neck angle.