For me, on my REO with an RM2 coiled at 0.8 - 1.0 Ohms, I generally get about 12 mL of liquid per 18650. When I pull the cell, they are typically at 3.6 - 3.7 and it's too cool of a vape for me at that point. I have no idea how many toots that is but, generally speaking, a good 18650 will last...