Understanding BAC

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What is BAC?

BAC stands for blood-alcohol concentration. It represents the percentage of alcohol in a person’s blood, which, in turn, reflects how drunk they are. Checking an impaired driver’s BAC helps law enforcement determine whether the driver is too impaired to drive.

How to check your BAC

A good place to start is a BAC calculator like the one below. Simply compare your gender and weight with the number of standard drinks you had.

This chart is only a tool for estimating BAC. Do not rely on this information to determine whether you are okay to drive after drinking. You can be arrested for any degree of impairment. Be aware. Know the effects. If you have consumed any alcohol, don’t drive.

Male or Female?

Your Body Weight

Type of alcohol

Number of Drinks

Time since first Drink

How alcohol affects you

Chances are, you’ve had some experience with alcohol, and you know what it feels like to get a buzz. But let’s break it down a little more. Alcohol is a depressant, which means it depresses—or, slows down—the nervous system. That means slow reactions, slurred speech and, after enough drinks, unconsciousness.

The most well-known effect is lowered inhibitions. Alcohol actually affects the part of the brain that controls it, which often leads to more (or louder) talking and disorderly behavior.

How your body processes alcohol

The liver is the body’s workhorse, processing alcohol to wear off the effects. On average, it takes about an hour to process the alcohol in a “standard drink,” though this can be different depending on weight, gender and other factors. A “standard drink” refers to 12 oz of 5% beer, 5 oz of 12% wine or 1.5 oz of 40% hard alcohol.

Quick facts and common misconceptions

One of the most common effects of drinking too much—vomiting—doesn’t get rid of the alcohol in your body. In fact, it doesn’t lower your BAC at all.
Eating before drinking can slow down your body absorbing alcohol (meaning you’ll feel drunk more slowly), but it doesn’t decrease your BAC.
Someone who reaches a BAC of .25% at midnight will still be over the legal limit of .08% at 10am. Meaning they’re still not safe to drive even 10 hours later.

The faster you drink, the higher your BAC.

It’s not rocket science: if you drink alcohol faster than your body can process it, you’ll get drunk faster. Generally speaking, drinking one standard drink per hour will maintain your BAC, whatever it is.

Gender matters too.

Surprisingly, some studies show that women process alcohol 10% faster than men. However, thanks to several other factors, most women will still have a higher BAC than men after drinking the same number of drinks.