Vaping, Electronic cigarettes

Let’s take a look at a hypothetical “medium” strength e-liquid that contains 12 milligrams of nicotine. This means that there are 12 milligrams of nicotine per milliliter. 5 milliliters is about one teaspoon. So, if you use one teaspoon of e-liquid, you will have ingested a little less than 60 mg of nicotine. To give you a sense of how this compares, American cigarettes contain, on average, about 9 mg of nicotine each. However, when you smoke a cigarette, most of the nicotine is burned off or lost due to other inefficiencies so your body only actually ingests about 1 mg of nicotine per cigarette. So a teaspoon of 12 mg e-liquid is equal to about 60 cigarettes. However, inefficiencies in vaporizing make it likely that this number quite a bit less also, but studies have not yet been done to give us an exact number.

http://www.virginvapor.com/blogs/news/3926612-how-do-i-choose-an-e-liquid-strength#