It depends - if I vape mostly on a my standard eGo batteries, 1.5 - 2ml. If I vape VV style (typically at higher wattages than the standard eGos) then consumption goes up to around 3ml. I'm including the small amount of "dregs" that's usually left at the bottom of a nearly empty tank in my dail total. It's dark and viscous, so I usually just rinse it out (probably accounts for .3 - .5ml).