I figure when I purchase juice on 5 ml a day & I usually purchase 2 or 3 months worth. Last juice order I bought 450 ml for a 3 months supply. Well, I vape much less than I thought, I got 250 ml left & it's been 2.5 months. And I have a bottle that has about 5 or 6 days worth left! That still didn't stop me from buying another 400 ml Saturday. Looks like I vape 3 ml or less, except weekends, it's more.