I smoked tobacco for over 40 years, about 25 cigs a day. Now the I'm vaping I use 5-6 refilled cartridges a day. I put 4-5 drops in a cartridge with out cleaning them out, I am sure I am getting about 3-4 tobacco cigs out of each cartridge using 18mg juice. A 30ml bottle of juice will last me about 3-4 weeks. Juice usage doesn't seem mush diffrent with my 510 or 4081.