It depends on the kind of material to be processed, the depth of the drilled hole and the removal power of the reamer.
With the machine reamers you have to remove about:
- 0.2 mm for a 6 mm hole
- 0.3 mm for a 12 mm hole
- 0.5 mm for a hole of 50 mm
With the hand reamers you have less removal material. About 0.08 mm to 0.13 mm.
Anyway the hole shouldn't be widened more then 5% of the initial ø.