If it's one vial, and it's supposed to be 12iu, they you should only put in 1.4cc at the max
10 IU = 1ml approx (most gH syringes have numbers going from 10-100)
So in order to get 12iu, you need to have 1.2 cc of water mixed in to make 120 units. I said 1.4 because you always overdose a little bit to account for some liquid staying on the needles when you withdraw.