Because the body absorbs nicotine from smoking and vaping in different ways, it is not possible to give an exact like-for-like comparison.
Studies suggest that smoking one cigarette results in the body absorbing 1-2mg of nicotine, so ten cigarettes a day is equivalent to 10-20mg of nicotine and 20-a-day is equivalent to 20-40mg of nicotine.
By comparison, a 2ml disposable vaping device with the maximum nicotine concentration allowed in the UK would contain 40mg of nicotine – the equivalent of a strong packet of cigarettes.