There is no tobacco in nicotine vaping so vaping = 0 tobacco cigarettes. If you must.... For my e-juices to = 400 cigarettes worth of nicotine or averaging 4800mg of nicotine (12mg per cigarette worth of nicotine on the average), I would need to vape 800 mls of e-juice in 20 days. This feat takes me 7 months. To = 1 pack of cigarettes (20 cigarettes) worth of nicotine I need to vape 40 mls In a single day but this is 8 days of me vaping.  When I was a smoker 20 packs of cigarettes (20 per pack) 400 cigarettes would take me 20 days to smoke. This is 7357 chemicals per 1 tobacco cigarette when lit and about 600 before lit on fire. Even before the cigarette is lit it has more chemicals than vaping.       This is 147,140 chemicals per pack of cigarettes not going into my body.  2,942,800 chemicals over 400 cigarettes. The average nicotine vape has under 5% and the cancer risks of a .5% of the chemicals which most can't be distinguished from the air we currently breathe in (outdoor air) having more cancer risks. I would need to vape 8018 mls of e-juice 70 months or almost 6 years of vaping to = 20 packs of tobacco cigarettes of chemicals. This is the very definition of harm reduction.