Blood Alcohol Concentration (BAC) Calculator - BAC Calculator & Drunk Driving Calculator
Free BAC calculator to estimate Blood Alcohol Concentration from alcohol consumption. Blood alcohol concentration (BAC) is a commonly used measure of alcohol intoxication, also known as drunkenness. It is typically expressed as a percentage of alcohol per volume of blood. Calculate BAC for beer, wine, liquor, and other drinks based on your body weight, gender, and time since first drink.
Last updated: January 20, 2026
Need a custom medical calculator for your platform? Get a Quote
Amount of Alcohol Consumed
Enter weight and alcohol consumption to calculate BAC
Legal BAC Limits
In the US, the legal limit for BAC when driving is 0.08%. Drivers who are over the age of 21 (the legal drinking age in the US), who have a BAC equal to or greater than 0.08%, can face penalties. Penalties for those under the age of 21 are stricter, but vary by state. For those under the age of 21, the legal limit ranges from 0.01% to 0.05%.
It is important to note that even if your BAC is below the legal limit, you may still be impaired. Impairment can begin at BAC levels as low as 0.02%. The safest approach is to never drive after consuming any amount of alcohol. Always use a designated driver, rideshare service, or alternative transportation.
Effects by Blood Alcohol Concentration
| BAC (%) | Behavior | Impairment |
|---|---|---|
| 0.001–0.029 | Average individual appears normal | Subtle effects that can be detected with special tests |
| 0.030–0.059 | Mild euphoria, Relaxation, Joyousness, Talkativeness, Decreased inhibition | Concentration |
| 0.060–0.099 | Blunted feelings, Reduced sensitivity to pain, Euphoria, Disinhibition, Extraversion | Reasoning, Depth perception, Peripheral vision, Glare recovery |
| 0.100–0.199 | Over-expression, Boisterousness, Possibility of nausea and vomiting | Reflexes, Reaction time, Gross motor control, Staggering, Slurred speech, Temporary erectile dysfunction |
| 0.200–0.299 | Nausea, Vomiting, Emotional swings, Anger or sadness, Partial loss of understanding, Impaired sensations, Decreased libido, Possibility of stupor | Severe motor impairment, Loss of consciousness, Memory blackout |
| 0.300–0.399 | Stupor, Central nervous system depression, Loss of understanding, Lapses in and out of consciousness, Low possibility of death | Bladder function, Breathing, Dysequilibrium, Heart rate |
| 0.400–0.500 | Severe central nervous system depression, Coma, Possibility of death | Breathing, Heart rate, Positional alcohol nystagmus |
| >0.50 | High possibility of death |
Alcohol and Health
Alcohol consumption has a number of short-term, as well as long-term effects. Short-term effects include dehydration and intoxication, while more long-term effects can include changes in the metabolism of the liver and brain. Alcohol consumption can also result in alcoholism, which is generally described as the use of alcohol that results in problems with mental or physical health.
Many studies regarding the effects of alcohol on health have been performed. Although there are some studies that support the conventional wisdom that a glass of red wine a day can have potential health benefits, these claims have not been rigorously proven. While some people may experience certain health benefits as a result of consuming some alcohol daily, not all people will, and the benefits do not come without risk.
Although alcohol, in moderation, is not necessarily deleterious, and may even have some positive benefits, more recent studies recommend that alcohol should not be consumed for its potential health benefits. While light or moderate alcohol (~1 drink per day: 12 fl oz beer, 5 fl oz wine, 1.5 fl oz distilled spirits) drinkers can certainly remain healthy, and may experience some health benefits, it is not fully known whether these benefits are worth the potential risks, since the potential benefits are relatively small compared to the risks.
Potential Health Benefits of Light to Moderate Drinking
- Reducing the risk of developing and dying from heart disease
- Reducing the risk of ischemic stroke
- Reducing the risk of diabetes
Again, these are only potential benefits, and consuming any amount of alcohol may not necessarily result in these benefits. Also, even light to moderate drinking can increase the risk of certain cancers, and of course, driving while intoxicated can have many severe consequences.
Risks of Heavy Drinking
Furthermore, drinking can lead to alcoholism, and heavy alcohol use has no health benefits. Heavy drinking, as defined by the Mayo Clinic, is having more than three drinks a day for women and men over 65, and more than four drinks per day, or more than 14 drinks a week for men younger than 65. Excessive drinking can result in serious health issues, including:
- Increased risk of certain cancers
- Sudden death as a result of pre-existing cardiovascular disease
- Heart muscle damage that leads to heart failure
- Stroke
- High blood pressure
- Liver disease
- Accidental serious injury or death
- Brain damage
Overall, a person should not begin drinking for potential health benefits. Those who already drink light to moderate amounts, who have not experienced negative health effects, can probably continue drinking moderately as long as they are not at risk for becoming heavy drinkers and continue to be healthy. Most importantly, a person should consult their doctor regarding their alcohol consumption to determine what is safe for their particular situation.
Need help with other medical calculations? Check out our blood pressure calculator, GFR calculator, and other medical tools.
Get Custom Calculator for Your PlatformFrequently Asked Questions
Found This Calculator Helpful?
Share it with others who need help with BAC and alcohol safety calculations
Suggested hashtags: #BAC #Alcohol #Safety #Calculator #DrunkDriving