You get about 1 mg of nicotine per cig. So a pack of cigs would yield roughly 20 mg of nicotine. At 16mg/ml, it would probably take 2 ( probably 3) pre-filled cartomizers to equal a pack of cigs.
Your batts will probably last 1.5-2 hours, depending on how much you vape.
You will love it I guarantee it.