You can't convert it directly because nobody knows for sure how much nicotine we are actually absorbing when we vape. We do know that when we smoke we are absorbing between 1mg-3mg per cigarette depending on the brand. Marlboro reds have about 1mg per cig. If you smoke a pack a day you are getting about 20mg per day of nicotine.
When we vape we absorb somewhere between 10%-40% of the nicotine we inhale. So If you use 24mg e-liquid (that's the average) and go through 3ml per day (that's also the average) then you get somewhere between 7.2mg-28.8mg -- nobody knows for sure exactly how much.
The best advice I can give is try a few different mg strengths... If you still crave cigs all day then use a higher mg, if you vape for a few minutes and feel dizzy or nauseous then lower your mg, if you vape and feel ok and forget to smoke then you probably found the right mg for you. Don't be too afraid of o.d.ing on nicotine because all it does is make you feel oogy, it's not that bad.
And don't be too afraid that you'll become even more addicted to nicotine if you get too much either because nicotine in this form is not actually all that addictive, it's only when combined with the MAOI's that you get from tobacco products that nicotine becomes extremely addictive. Vaping will actually make you less addicted -
even if you end up using more nicotine.
Good luck!!
