Blood Alcohol Concentration (BAC)
What is BAC?
Blood alcohol concentration (BAC) is a measure of the amount of alcohol that is present the blood, based on the volume of alcohol consumed over a given period of time. A BAC of .10% means that an individual's blood supply contains one part alcohol for every 1000 parts blood.
There are many factors that affect BAC, and not everyone’s BAC rises and falls at the same rate. That means that even if two people drink the same amount of alcohol, over the same length of time, their BACs can still be different.
Factors Influencing BAC
- Quantity: the more standard drinks, the higher the BAC.
- Rate: the quicker drinks go down (beer pong and other drinking games) the quicker the BAC rises.
- Gender: even pound-for-pound, drink-for-drink, people assigned female at birth get drunk faster than people assigned male at birth.
- Body composition: is your body changing? More fat makes BAC go up faster.
- Body weight: smaller bodies have less ability to dilute alcohol, which equals higher BAC.
- Stomach contents: if you don't eat immediately before drinking, alcohol is absorbed more quickly
- Dehydration: dehydration reduces blood volume and the amount of water in muscle, so there is less dilution of alcohol and BAC rises.
Did you know?
The rate of alcohol leaves your body is constant regardless of gender and body size.
Feeling overwhelmed with exams and papers? Stressed people feel the effects of alcohol quicker.
Pulled an all-nighter? Tired people feel the effects of alcohol faster.
BAC Calculator: This tool can be used to estimate Blood Alcohol Concentration. Other factors not examined by this tool may also play a role in BAC levels.
Interactive Body Tool: See how alcohol affects the human body.
IF A PERSON WENT TO BED AT 2:00 a.m. WITH A B.A.C OF .20 THE NEXT 15 HOURS MIGHT LOOK LIKE THIS:
|
TIME |
BAC |
ACTIVITY |
|---|---|---|
|
2:00 a.m. |
.200 |
Leave the party, get food, stumble home |
|
3:00 a.m. |
.185 |
Drunk text friends |
|
4:00 a.m. |
.170 |
Crash in chair |
|
5:00 a.m. |
.155 |
Awake with neck cramp, move to bed |
|
6:00 a.m. |
.140 |
Restless sleep |
|
7:00 a.m. |
.125 |
Wake up, search for water, go back to sleep |
|
8:00 a.m. |
.110 |
Restless sleep |
|
9:00 a.m. |
.095 |
Hit snooze repeatedly – pounding headache |
|
10:00 a.m. |
.080 |
Realize you accidentally shut o the alarm, jump out of bed, pull on sweats, grab gum, hustle to class (DUI possible if you drive) |
|
11:00 a.m. |
.065 |
Contemplate whether food is a good idea – decide it’s not – go home and sleep (still restless sleep) |
|
Noon |
.050 |
Alarm wakes you – contemplate skipping next class |
|
1:00 p.m. |
.035 |
In class, irritable |
|
2:00 p.m. |
.020 |
Head clearing, skip the gym and go home |
|
3:00 p.m. |
.005 |
Feeling better, decide to eat |
|
4:00 p.m. |
.000 |
Finally sober (If you are under 21 you could not legally drive until this point) |
|
5:00 p.m. |
Consider making plans for the night that don’t involve drinking |
|
|
Amended from: www.uhs.umich.edu/aodresources |