Depends on the potency of the nicotine PG you purchased. Then you can use a e-liquid caculator to figure it out. e-Liquid Calculator This is the easiest caculator that I use, I like this one. To find "only" the amount or nicotine you need to use just set your target amount to make your total PG that youre gonna put in your recipe (since I gave out the entire recipe in amounts) then type in your target strength of nicotine, which you are wanting 6mg, then leave water/vodka/pga at 0, leave VG at 0, and put PG at 100%, then put how ever strong your nicotine juice is that you purchased, put 100% PG if thats what your nicotine is based in (Most is) then just scroll down and it will tell you the amounts to use. In this case, it says Im to use 2.88 nic PG & 9.12PG.....in this case I'd just round it and put 3ml of Nic PG % 9ml of reg PG. Hope that helps! The caculator most definately does! If you need any more help feel free to ask! 