Think of mg/ml like a concentration. A 10 ml bottle at 10 mg/ml has 100 mg of total nicotine. Double the strength to 20 mg/ml and the same bottle now has 200 mg. The number of puffs you take doesn't change the math—each puff delivers a certain amount based on the strength and your device's output.

Two things to know right now:

• Freebase nicotine is the older form. It's harsher at higher strengths, so you'll usually see it at 3, 6, or 12 mg/ml.
• Nicotine salts are smoother, which is why disposables can carry 20, 30, or even 50 mg/ml without feeling like sandpaper.

If you see a high number like 50 mg/ml on a disposable, it's almost certainly a salt. That's normal, but it doesn't mean you should start there.