Easy way to figure it out, divide your full nic mg/ml by your goal mg/ml nic. That = total units, so lets say 36mg nic/6 (desired mg per ml)=6 so 6 units. 1 unit will always be nic, the rest is VG (or both VG and PG whatever your ratio is). For you the ratio would be 6 units, minus 1 = 5...