Most people begin that one e cigarette cartridge is equal to one pack of cigarette. But that belief is not always true if the nicotine levels are not the same across the board. So when someone ask, does one puff on a e cigarette equal one puff on a regular cigarette? I have to tell them no.
For example, if you are used to smoking a high nicotine cigarette and then you switch and use a lower level nicotine cartridge with your ecigarette then you are going to need to take more puffs on your ecigarette to get the same amount of nicotine into your body. Hence, you will be smoking more on your ecigarette and and your e cigarette will not as long as a pack of regular cigarettes.
So you are really compare apples to oranges unless everything is equal with the nicotine level.