The plans have us drill to 11/32, then ream to 3/8 (9.5mm); so by the plans the drill is 1/32 under. 11/32 is 0.344.
For the 3/8, that is 0.031 under, and for the 9.5 mm that is 0.030 under. I don't think my drill press is perfect though. It probably is slightly off, but I can't tell how much.