Long enough for me. Ok that lol. I usually take mine in 10 minute bursts. (I take it out and save it in the small section on the back) Then about 30 minutes later, go for another 10 minutes. They start to wear down on the third go. So probably around 30 minutes ish.  

 Just went back to 3mg zyn they usually are good for an hour 

much better than smoke or vape