The rate at which blood alcohol concentration (BAC) decreases in the human body can vary based on several factors. These include an individual’s metabolism, the amount and type of alcohol consumed, the person’s body weight, age, gender and overall health.
However, on average, the human body processes alcohol at a rate of about 0.015 to 0.020 grams of alcohol per deciliter (g/dL) of blood per hour. This means that your BAC will typically decrease by about 0.015 to 0.020 g/dL per hour, with only slight variations based on these other factors. This rate is important to identify for those who are going to be driving and want to know how long to wait to get behind the wheel after drinking.
How BAC metabolism works
For someone with a BAC of 0.08 g/dL (which is the legal limit for most drivers, other than commercial drivers or underage drivers), it would take roughly 4 to 5 hours for their BAC to reach 0.00 g/dL if they do not consume any more alcohol during that time.
Keep in mind that consuming more alcohol during this time will slow down the rate at which BAC decreases. Hydration, food intake, and other factors can also have an impact on how fast the body metabolizes alcohol.
How fast does it increase?
How fast someone’s BAC goes up also depends on numerous factors. Many people reach 0.08% after around four or five drinks. But things like weight and gender make a big difference. A 250-pound man could consume much more alcohol than a 100-pound woman before he would hit the legal limit. Every driver needs to understand their own body’s response to intoxication.
It’s also important to note that these are rough estimates, and individual variations can be significant. No one should ever assume they are under the limit. The only surefire way for someone to reduce their BAC to a safe and legal level for driving is to allow sufficient time for their body to metabolize the alcohol they’ve consumed. Those who have been arrested on allegations of impaired driving, especially if they believe they waited long enough, need to know what legal defense options they may be in a position to use to fight their charges. Seeking legal guidance is a good first step forward.