The issue is what are you trying to do? How precise must the hole be that you are trying to drill? If you are drilling a blank for a pen tube, what is the actual OD of the tube (12.5mm is probably a nominal dimension).
My guess is that the answer is that it is close enough, but without knowing the exact circumstances, we can't be absolutely certain.
It's for a blank for a Panache pen kit. I will try the 31/64. I think that should work. Thank you all for your input. It did help a lot
Thanks again
Jallan
The way I decided which bit to use in the past was to measure the tube then decide............. do I want to drill a few thousandths over and have room for plenty of epoxy OR drill a few thousandths under and have the tube fit so tight that it scraped off 93% of the epoxy when shoving the tube in. I dislike glue starved joints so I opted for the 1/2" bit and plenty of glue!
I used a 31/64" once when I couldn't find my 12.5mm and I thought the fit was to tight, there was hardly any room left for epoxy. Maybe drill bits from different manufacturers vary a little but that was my experience.
The 12.5mm drill bit I bought on Amazon drilled a 12.3mm hole, with no room for glue. I just went to using a 1/2" bit, which drills about 12.7mm, and lots of glue. Gorilla glue on wood, epoxy on acrylic.