Actualy depends on how many of those you smoked. What you can do is: look on the cigarette-box to find how much nicotine it says on that (in mg). Light would perhaps be 0.5 mg, or in fact anything up to 0.7 (0.8 is where 'normal' starts).
When you have found that (that's the mg per cigarette): then multiply that figure with the number of cigs you smoked daily.
Remember the outcome: that's the total day-usage you will be looking to replace with e-smoking (maybe lowering it at a later stage; I wouldn't lower it too much to start out with though, myself; though some seem to fare well with that).
And then, looking at the e-smoking side, it depends on your style and frequency of smoking, which strength you will be going for. A lot of people find they are e-smoking more consistently then they did as tobacco-smoker, meaning they in fact would get more nicotine in if they had kept to their former daily usage number as to which e-strength they chose.
But with e-smoking you can vary, so you can adapt to this changed pattern (if it happens: likely, not certain) by going to a lower strength (lower strength x longer smoking = shorter smoking x higher strength) (and zero strength x endless smoking stays zero: the ultimate goal perhaps
)
Hope this helps to find your way, good luck!
