Its hard
So, 1 g of flower containing 20% THC should contain 0.2 g (200 mg) of THC by weight
Hegyi P, Prniczky A, Lerch MM, Sheel ARG, Rebours V, Forsmark CE, et al

Independent research found e-cigarette packaging nationwide is often misleading or even completely inaccurate on the products nicotine level.[2] Sometimes e-cigarette packages claim the device contains no nicotine, but when tested the product in fact contained high levels of the addictive and harmful substance.[3] Some studies compared JUUL pods to a pack of cigarettes, and the claim one pod was roughly equivalent to one pack of cigarettes.[4] However, the studies found the amount of nicotine varied dramatically from pod to pod, making any comparison loose at best.[5] JUULs popularity has decreased over the past several years, with brands like Vuse and Puff Bar increasing in sales, each with their own formulations.[6] An early e-cigarette study published in Nicotine & Tobacco Research compared different e-cigarette brands for 15 puffs and saw nicotine levels varying from 0.5 milligrams all the way up to 15.4 milligrams.[7] Newer e-cigarettes may also contain much larger e-liquid reserves, further clouding the calculations

In a very short amount of time, youll find it much easier to behave naturally in social situations and that might turn out to be the most positive effect of switching to vaping