I'm going through about 2-3ml per day myself...some days I'm on the higher end other days near the lower. It's averaging out to almost three though. I think I could get more out of a top off, but I like the full flavor of whatever I'm vaping so I tend to top off frequently. I also notice that I vape more if the nic level is lower...which is deliberate. If I'm puffing away all day, I tend to want a lower level of nic. If I'm taking a break, like I would with a cigarette, then I go a little stronger.