I would need to know the following:
What volume (in ml) of liquid you'd like when you're done
What mg strength the concentrated nic liquid is
What mg you want to be at (I'm assuming 12)
Once you know these
three, you can determine how much nic liquid to add.
For example, I start with a 48mg base liquid, and I always fill up 15ml bottles. I like my
juice at 9mg.
48mg base liquid x 3ml/15ml = 9ml liquid.
That's my 48mg base, times 3ml of it, divided into the 15ml of
juice I'm making.
If I wanted 12mg liquid, I would use 3.75ml of that base, since 48mg x 3.75ml / 15ml = 12mg.
If my base liquid was 60mg, I would use 3ml of it to make 15ml of 12mg liquid, since 60 x 3/15 = 12.
Hope that helped...