In practice it is impossible to equate the amount of nicotine in a raw cigarette or in
e-liquid with the final result. The only valid measure is
simply to get what you need. Most people would probably feel the best advice is to cut your
eliquid gradually with VG or doubler, and when you get down to a level that makes you still crave a cigarette, then up it a bit.
Some of us vary the nic level through the day, this method works fine for many: for me it's medium strength in the a.m., high in late afternoon / early evening when I crave a cig most, low in the late evening before bed. I also have a super-strength mix I hit if I'd rather vape than smoke but the craving is strong.
There is a ton of maths you can do on this but my feeling is it's all a complete waste of time: just tweak your nic level until it's right, which is all you are trying to do in any case. Reduce till you've gone too far, then come back up.
For example here is some of the data:
- For both tobacco cigarettes and e-cigarettes it is reported that only one-tenth of the nicotine in the raw product is available to the user (ie the nic in raw tobacco or in e-liquid).
- Every published clinical trial of e-cigarettes shows that nicotine and nicotine metabolite blood levels were around one-tenth of the equivalent level for a cigarette smoker
or lower - in other words they don't work well for delivering nicotine. However these trials were all conducted under the worst possible conditions for actually getting an ecig to work, so we still don't know the real numbers.
- Also, any experienced user will tell you they can get a nic OD rush if they adjust the various factors to optimum.
- Personal nicotine blood tests published have shown blood nicotine levels up to one-quarter as high as for the equivalent cig smoker, for just one of the three most common substances tested for (nicotine and metabolites), the other two being far below cig smokers' levels. Thus everyday tests on experienced users show a much-reduced level of nic in the blood compared to smokers.
- Nobody knows how much nicotine is in inhaled vapor. Going by what tests show on both new and experienced users, there is far less available than for cigarettes. There is a serious anomaly in these results somewhere since experienced users can OD if they try hard.
Since there are no accepted hard numbers for either the nic content of vapor, or even for blood nic levels, it's safest to just suck it and see. You could certainly try to work it out by using various measurements but the end result would not only be fallible but probably farcical. Everybody is so completely different in their tolerance for various substances that only the individual's experience is of any value.
Just cut down to the point where you need more, then raise it.