The BAC rises more rapidly in those who drink on an empty stomack, because there is no food in which to dilute the alcohol. The type of alcohol you drink. Type of mixer used. Water and fruit juices mixed with alcohol slow the absorption process, while carbonated beverages will speed it up. Temperature of the drink.
Warm alcohol is absorbed quicker than cold alcohol.
If you are male or female. Therefore, a man and woman, with all other factors being equal, both drinking the same amount of alcohol will have different BAC levels. Hers will be higher. A woman's menstrual cycle will also affect her rate of absorption. They will experience their highest BAC's premenstrually.