I'm a complete newbie at this, so I had (and still have) a lot of questions like yours. I found a chart online that lists nicotine content by brand of cigarette. Just google it.
So if you're talking about nicotine content, then take the following example. Each bottle's strength is represented in mg/mL. So a 10 mL bottle of 18mg liquid would contain 180mg of nicotine in total. Simply, 1 mL has 18 mg of nicotine. A Marlboro light has 1.7mg of nicotine (or somewhere thereabouts), so in theory 1 mL of
juice contains about 10 analogs worth of nicotine...give or take.
Now does that mean that going through 1 mL of
juice will FEEL like smoking 10 cigarettes, or that if I smoke half a pack a day I can expect to go through about 1 mL of liquid a day??? I don't know.
What I'm told by members here is that eventually I'll figure out what works for me after some experimenting and acclimatizing. I'm expecting my first pv, a 901, in the mail tomorrow, and I'm very excited!
I'm not sure if I answered your question, but I hope that helps.