What is Blood Alcohol Concentration (BAC)?


Author: Thomas Roth

Last Updated: 11/15/2021

Blood alcohol concentration (BAC) is a measurement used to measure the amount of alcohol in someone's blood. BAC measurements became popular as drunk driving laws became more prominent and it continues to be used to monitor how much alcohol someone has consumed. While BAC is used for drunk driving, the percentages can also indicate if someone has consumed too much alcohol and requires medical attention.

What is BAC Used For?

BAC is used to measure the amount of alcohol present within someone's bloodstream. The measurement is in grams per milliliter of blood and indicates how much alcohol someone has consumed. While it can be used for medical purposes and treatment, it's often used to expose people who may have been drinking alcohol and driving.

BAC can also be used to determine if someone has been drinking during a rehabilitation program or if someone has alcohol poisoning. Alcohol poisoning is a life-threatening condition that can cause death if left untreated.

What are the Factors that Impact Blood Alcohol Concentration (BAC)?

Several factors like height and weight impact the levels of BAC in someone's body. That said, the factors are not always consistent.

The factors that influence BAC levels are:

  • Gender 

  • Age

  • Weight

  • Health history 

  • Height 

  • The amount of alcohol consumed

  • How fast alcohol was consumed

  • If someone has diabetes 

  • Alcohol tolerance 

  • Medications 

  • Hydration

There are 100s of factors that play into BAC levels but these are the most common to watch out for.

What are Blood Alcohol Concentration (BAC) levels?

Blood alcohol concentration (BAC) is the metric that's used to measure how much alcohol is in someone's blood. The measurement is called blood alcohol concentration (BAC). BAC levels vary from person to person but the liver can process about 1 standard drink per hour (about 12 ounces of beer).

Once the liver falls behind BAC levels begin to rise. This is when people start to experience the impact of alcohol on the body. People with BAC levels over .08% also shouldn't drive in the United States because it is illegal and can result in a DUI charge.

What are the Effects of Blood Alcohol Content? 

The more someone drinks the higher their BAC levels will be. People with high BAC levels will experience side effects that worsen as the number gets higher. Below we have the BAC levels and how they affect the body.

1. .02% of BAC

At .02% BAC alcohol doesn't have much effect on the mind or body and people may still feel sober. That said, there are some changes to note that include:

  • Slight euphoria 

  • Shyness decreases

  • Slight relaxation

At these early stages, the impact of alcohol is rarely noticed but some people may begin to feel buzzed.

2. .05% of BAC 

At .05% of BAC people will begin to feel buzzed as alcohol starts to take effect. The brain begins to slow down and these effects can be felt:

  • Lower inhibitions (minor)

  • Impaired judgments (minor)

  • Lowered caution (minor)

  • Increased risk-taking behavior 

  • Euphoria

  • Slightly impaired memory

  • Feeling warm

  • Feeling relaxed

  • Flushed appearance

During this stage, the effects of alcohol begin to be felt as the majority of drinkers become buzzed during this stage.

3. .08% of BAC 

.08% BAC is when people begin to feel more serious symptoms of intoxication and impairment progresses.

At. 08% people begin to experience:

  • Impairment of speech (minor)

  • Balance becomes unsteady 

  • Euphoria

  • Blurred vision

  • A decline in reasoning and memory

  • Slowed reaction time

  • Trouble with concentration and hearing 

  • Self-control declines 

.08% affects everyone differently but this is when people settle into the buzzed stage or start to feel drunk.

4. .10% of BAC 

.10% of BAC is when significant effects of alcohol intoxication begin. The body and mind slow down and people become less coordinated and coherent.

At .10% of BAC people begin to experience:

  • Impairment of fine motor functions and skills

  • Loss of good judgment 

  • Speech might start to become slurred 

  • Reaction time is much slower

  • Peripheral vision becomes blurry

  • Hearing becomes more impaired 

  • Memory impairment worsens 

At this stage, most people are drunk and begin to become belligerent.

5. .15% of BAC 

Once people reach .15% severe symptoms of alcohol intoxication occur. Judgment gets worse and Impairment continues to slow brain function and reaction time.

People at the .15% level of BAC experience:

  • Major losses in balance 

  • Slurred speech 

  • Motor function becomes worse 

  • Blurred vision and hearing

  • Euphoria begins to fade to dysphoria (state of being not well)

  • Nausea and vomiting begin to appear 

People at .15% BAC can also start to lose the ability to make short-term and long-term memories, which leads to blacking out and loss of consciousness.

6. .20-.29% of BAC  

When some reach a BAC of .20-.29% people will need help to walk and the brain begins to lose the ability to form memories.

People at .20-.29% will experience:

  • Loss of consciousness

  • Need help to walk or remain standing 

  • Severe mental confusion 

  • Aggressive behavior 

  • Vomiting

  • Nausea

  • Dysphoria

  • Risk of blacking out increases 

  • Risk of alcohol poisoning increases 

At a BAC of .20-.29% the level of alcohol in one's body becomes dangerous. People might need medical attention or supervision during this phase.

7. .30-.39% of BAC 

.30-.39% BAC is when alcohol poisoning begins to occur. During this stage people will experience:

  • Alcohol poisoning

  • Uncontrollable vomiting that leads to choking 

  • loss of consciousness

  • Blacking out 

People within this BAC range need to seek medical attention and can die if left untreated. If medical attention is not possible people need to be hydrated and turned on their sides.

8. .40% and over of BAC 

Once someone reaches a BAC of .40% coma and death from alcohol poisoning are highly likely. At this stage, people will experience:

  • Coma

  • Death

  • Alcohol poisoning 

  • Uncontrollable Vomiting and choking 

  • Seizures 

Once BAC levels reach this point the risk of death increases and the brain begins to shut down.

How to Prevent BAC's Effect based on Different Levels 

Preventing BAC's effects at different levels is similar for each BAC level. The prevention methods for .02% BAC and .10% BAC don't change much because there isn't a lot you can do to reduce the effects of BAC. That said, there are ways to prevent sudden BAC spikes and methods to sober up faster.

Here are the best tips to reduce BAC effects at each level:

  • Allow time between each drink

  • Stay hydrated and drink water between each alcoholic beverage 

  • Make sure you eat a nutrient-dense meal before drinking

  • Keep track of how many drinks you're having 

  • Dilute distilled beverages (liquors, spirits) to reduce their alcohol concentration

  • Don't drink too quickly –sip instead of chugging 

  • Sleep it off

  • Exercise can increase the speed at which alcohol is metabolized 

Reducing the effects of BAC can also be done by consuming beverages like coffee that increase heart rate and speed up metabolism.

Table of Blood Alcohol Concentration Effects 

BAC Levels 

Effects of BAC Levels 

.01% to .03%

  • Slight mood changes (euphoria)

  • Feeling and looking flushed

  • Decline in shyness 

  • Depressive effects of alcohol are not felt yet

.04% to .06%

  • Sensations of relaxation

  • Euphoria 

  • Feelings for warmth and comfort

  • Slight impairment of memory

  • Slight impairment of coordination 

  • Declining decision-making skills 

.07% to .09%

  • Euphoria

  • Relaxation 

  • Balance becomes impaired

  • Hearing impairment 

  • Blurred vision

  • Sweating

  • Increased risk-taking behavior 

  • Reduced inhibitions 

  • Frequent urination

.10% to .12%

  • Speech starts to become slurred

  • Balance becomes worse

  • Fine motor skills become impaired 

  • Impaired judgment

  • Impaired coordination

.13% to .15%

  • Major loss of balance

  • Severe impairment of motor control

  • Slurred speech

  • Decreased memory function

  • Euphoria subsides and turns to dysphoria 

  • Anxiety

.16% to .20%

  • Nausea begins to occur

  • Balance loss gets even worse

  • Dysphoria dominates mood

  • Changes in blood pressure

  • Sweating

  • Memory becomes severely impaired

  • Severe coordination impairment 

  • People at this stage begin to appear sloppy 

.25% to .30% 

  • Balance is lost and people need help walking

  • Loss of short-term and long-term memory creation

  • Mental confusion 

  • Loss of coordination 

  • Blurred vision 

  • Spinning sensation

  • Vomiting 

  • Dysphoria 

.35% to .39%

  • Loss of consciousness 

  • Trouble breathing

  • Uncontrollable vomiting that leads to choking

  • Seizures

  • Alcohol poisoning 

Above .40% 

  • Coma

  • Respiratory failure

  • Death 

What is a Moderate Level of Alcohol Consumption?

A moderate level of alcohol consumption is typically one standard drink per day for women and two standard drinks per day for men. That said, moderate levels of alcohol consumption vary from person to person based on the frequency of alcohol consumption.

One standard drink consists of:

  • 12 ounces of 5% beer 

  • 5 ounces of 12% wine 

  • 1.5 ounces of 40% distilled spirits

When someone consumes these alcohol amounts daily it's considered moderate drinking.

What is a Blood Alcohol Concentration Calculator?

A blood alcohol concentration calculator is a tool that's used to measure the amount of alcohol in a person's blood. BAC is measured in milligrams of alcohol found in 100 milliliters of blood. The BAC level is commonly listed as a decimal or percentage, with an example being .08% or .10%. Someone with a BAC level of .10% has one part alcohol per 1,000 parts of blood.

Most BAC calculators work by dividing the amount of alcohol consumed by the amount of time that's passed. BAC calculators will require information like gender, body weight, and time since the first drink to come to a more accurate estimation.

While BAC calculators have a high degree of accuracy, they shouldn't be used to determine if you're sober enough to drive.

The legal limit of BAC determines how much alcohol someone can consume before driving a vehicle. Most countries have a limit in place to prevent driving while intoxicated.

Here are the BAC levels based on countries:

  • Afghanistan: 0%

  • Albania: .01%

  • Algeria: .02%

  • Andorra: .05%

  • Angola: .06%

  • Antigua and Barbuda: No limit

  • Argentina: .05%

  • Armenia: .08%

  • Australia: .05%

  • Austria: .05%

  • Azerbaijan: 0%

  • Bahamas: .08%

  • Bahrain: N/A

  • Bangladesh: 0%

  • Barbados: None

  • Belarus: .03%

  • Belgium: .05%

  • Belize: .08%

  • Benin: .05%

  • Bhutan: .08%

  • Bolivia: .05%

  • Bosnia: .03%

  • Botswana: .05%

  • Brazil: 0%

  • Bulgaria: .05%

  • Burkina Faso: .05%

  • Cabo Verde: .08%

  • Cambodia: .05%

  • Cameroon: .08%

  • Canda: .08%

  • Central African Republic: .08%

  • Chad: .08%

  • Chile: .03%

  • China: .02%

  • Columbia: .02%

  • Congo: .08%

  • Cook Islands: .08%

  • Costa Rica: .05%

  • Croatia: .05%

  • Cuba: .01%

  • Cyprus: .05%

  • Denmark: .05%

  • Dominica: .08%

  • Dominican Republic: .05%

  • Ecuador: .03%

  • Egypt: None

  • El Salvador: .05%

  • Equatorial New Guinea: .05%

  • Eritrea: .05%

  • Estonia: .02%

  • Eswatini: .04%

  • Ethiopia: .08%

  • Fiji: .08%

  • Finland: .05%

  • France: .05%

  • Gabon: .08%

  • Georgia: .03%

  • Germany: .05%

  • Ghana: .08%

  • Greece: .05%

  • Guinea: .08%

  • Honduras: .07%

  • Hungary: 0%

  • Iceland: .05%

  • India: .03%

  • Indonesia: None

  • Iran: 0%

  • Iraq: .04%

  • Ireland: .05%

  • Israel: .05%

  • Italy: .05%

  • Jamaica: .08%

  • Japan: .03%

  • Jordan: .08%

  • Kazakhstan: 0%

  • Kenya: .08%

  • Kiribati: .08%

  • Kuwait: N/A

  • Lao People's Democratic Republic: .05%

  • Latvia: .05%

  • Lebanon: .05%

  • Lesotho: .08%

  • Liberia: None

  • Lithuania: .04%

  • Luxembourg: .05%

  • Madagascar: .04%

  • Malwai: .08%

  • Malaysia: .08%

  • Maldives: Total ban

  • Mali: .03%

  • Malta: .08%

  • Marshall Islands: None

  • Mexico: sub-national

  • Monaco: .02%

  • Mongolia: .05%

  • Montenegro: .03%

  • Morocco: .02%

  • Netherlands: .05%

  • New Zealand: .05%

  • Nicaragua: .05%

  • Nigeria: .08%

  • Norway: .02%

  • Oman: .08%

  • Pakistan: 0%

  • Palau: .10%

  • Panama: .05%

  • Paraguay: 0%

  • Peru: .05%

  • Philippines: .05%

  • Poland: .02%

  • Portugal: .05%

  • Republic of Korea: .05%

  • Republic of Moldova: .03%

  • North Macedonia: .05%

  • Romania: 0%

  • Russia: .04%

  • Rwanda: .08%

  • Saint Kitts and Nevis: .08%

  • Saint Lucia: .08%

  • Saint Vincent and the Grenadines: None

  • Samoa: .04%

  • San Marino: .05%

  • Saudi Arabia: Total ban

  • Serbia: .03%

  • Singapore: .08%

  • Slovakia: 0%

  • Slovenia: .05%

  • Somalia: 0%

  • South Africa: .05%

  • South Sudan: None

  • Spain: .05%

  • Sudan: Total ban

  • Suriname: .05%

  • Sweden: .02%

  • Switzerland: .05%

  • Tajikistan: .03%

  • Thailand: .05%

  • Timor-Leste: .05%

  • Tonga: .03%

  • Trinidad and Tobago: .08%

  • Tunisia: .05%

  • Turkey: .05%

  • Turkmenistan: .03%

  • Uganda: .08%

  • Ukraine: .02%

  • United Arab Emirates: 0%

  • United Kingdom: Subnational 

  • United Republic of Tanzania: .08%

  • United States of America: .08%

  • Uruguay: 0%

  • Uzbekistan: 0%

  • Venezuela: .08%

  • Vietnam: 0%

  • Yemen: Total ban

  • Zambia: .08%

  • Zimbabwe: .08%

It's important to note that the legal limit can change in each country depending on someone's age and criminal history.

How to Limit Your Drinking 

Limiting your drinking is the best way to prevent negative health effects and conditions like alcohol abuse disorder (AUD) AUD is an addiction to alcohol that becomes a dependence on the substance. While there are several stages of AUD, the condition is the most noticeable when people suffer from withdrawal symptoms when they stop drinking.

While AUD is a hard condition to treat, it can be done. You can find treatment in accredited addiction treatment centers and through groups like Alcoholics Anonymous (AA). That said, the best way to prevent and treat alcoholism is to stop consuming alcohol. 

Thomas Roth
Lead Editor

Thomas has been working in the substance abuse industry for over 3 years and he's made it his mission to help those in need. Tom started out by writing content to help people find addiction treatment centers near their location. Once he understood the value in the words he wrote Tom shifted to outreach, editing, and content creation. If nothing else, Tom wants to see those who struggle with Alcohol abuse disorder recover.