The syringe is a 1ml oral syringe, numbered at 0.1ml increments. Since it is 30mg/ml, 0.1 ml would give you 3mg. I take 3mg daily, so I fill to the 0.1ml line. If you want 6mg, go to the 0.2ml line. 5mg would be slightly less than that, but really it is too hard to get that precise.