In the engineering world, the fit is usually set by a variety of parameters like thermal expansion, max allowable runout, assemblibility, supplier capability, etc.
I know a 1.000" bar in a 1.000" hole sounds like it fits, but not without heat, dry ice and a BFH!
Now, the easier way to determine this is by using a table of fits
. Good book. It is kind of like a cheater's guide to engineering.