To establish the equivelent in vape to one cigarette we need to understand how the two are measured. A cigarette will containe between 0.1mg and 3mg depending on the brand or variety ie low low or high nicotine. If we take an average of that a pack of 20 medium strength cigarettes will contain 30 to 40mg of nicotine. A 10 ml bottle of 20mg per ml of e-liquid will contain 200 mg of nicotine. If we take the average that would equate to 6 to 8 packs of average strength cigarettes. A disposable vape usually contains 2ml of 20mg eliquid which is 40mg , the equivelent of a pack of medium strength cigarettes.