I smoked menthols and black and milds before I started using e-cigs. I bought a juice called insane and it tastes pretty good, it's 2.4% nic according to the bottle and being a newbie I'm not exactly sure what that means since the numbers don't correlate to anything I've seen so far. My best guess is that it means it has a low level of nicotine in the juice.
2.4% nicotine is roughly equivalent to 24 milligrams per milliliter. And again, a rough estimate, is 20 drops of ejuice is equivalent to one millileter. I have heard of blue cartriges holding about .8 millileters. So, a 24mg blu has roughly 19.2 mg of nicotine if you vaped the cartridge dry.
Now, the industry knows, vaping and smoking are totally different and there needs to be a study done on exactly how much nicotine is absorbed through vaping.. they pretty much realize it's different, but they don't know by how much. a popular belief is that vaping actually absorbs less nicotine, but no studies have been done.
With that out of the way, a reguar cigarette, say pall mall, has about 1.7 mg of nicotine. So, one blu cartridge holds the same nicotine as roughly 11 Pall Mall's.
I know there's going to be some backlash and corrections needed, so please chime in if I am wrong.