There are different sized tanks so it's going to vary because of that, how much you vape, and the equipment you are using. I've got a 6ml tank on my Silver Bullet and go 2 to 2 1/2 days on a filling. If I were using a 3ml tank I'd be refilling once a day. You aren't supposed to vape them all the way down. As to whether you're vaping too much, some people vape 10ml a day. If you're feeling a bit nauseous or getting a headache you're getting too much nicotine and should either vape less or lower your nic level.