BAC Calculator - Calculate Your Blood Alcohol Content

Our free BAC calculator helps you estimate your blood alcohol content based on the number of drinks consumed, your weight, gender, and time elapsed. Understanding your BAC can help you make informed decisions about driving and alcohol consumption.

What is Blood Alcohol Content (BAC)?

Blood Alcohol Content (BAC) is the concentration of alcohol in your bloodstream, measured as a percentage. A BAC of 0.08% means there are 0.08 grams of alcohol per 100 milliliters of blood. In the United States, it’s illegal to drive with a BAC of 0.08% or higher (0.04% for commercial drivers).

How BAC is Calculated

BAC is calculated using the Widmark formula, which considers:

For Men: BAC = (Alcohol consumed in grams / (Body weight in grams × 0.68)) - (0.015 × Hours since drinking)

For Women: BAC = (Alcohol consumed in grams / (Body weight in grams × 0.55)) - (0.015 × Hours since drinking)

The key difference is the distribution ratio: 0.68 for men and 0.55 for women, reflecting the fact that women generally have a higher body fat percentage and lower body water content.

BAC Calculator

Understanding BAC Levels and Their Effects

BAC Effects Chart

BAC Level	Effect	Impairment
0.01-0.03%	Mild euphoria	Minimal impairment
0.04-0.06%	Relaxation, warmth	Lowered inhibitions, minor impairment
0.07-0.09%	Slight impairment	Reduced coordination, impaired judgment
0.10-0.12%	Significant impairment	Slurred speech, poor coordination
0.13-0.15%	Major impairment	Gross motor impairment, blurred vision
0.16-0.20%	Severe impairment	Nausea, vomiting, blackouts possible
0.25-0.30%	Severe alcohol poisoning	Loss of consciousness, danger to life
0.35-0.40%	Life-threatening	Coma, respiratory failure, death possible
Above 0.40%	Potentially fatal	High risk of death

Legal BAC Limits in the United States

Standard drivers: 0.08%
Commercial drivers: 0.04%
Drivers under 21: 0.00-0.02% (zero tolerance laws)

Note: Even at BAC levels below the legal limit, your driving ability can still be impaired. The safest choice is not to drive after drinking at all.

Factors That Affect Your BAC

Body Weight

Heavier people have more blood and body water to dilute alcohol, resulting in lower BAC levels for the same amount of alcohol consumed. A 120 lb person will reach a higher BAC than a 200 lb person drinking the same amount.

Gender

Women generally reach higher BAC levels than men when consuming the same amount of alcohol because:

Lower percentage of body water (55% vs 68%)
Different enzyme activity (less alcohol dehydrogenase in the stomach)
Hormonal differences affecting alcohol metabolism
Generally smaller body size

Rate of Consumption

Drinking quickly leads to higher peak BAC levels. Your liver can only metabolize about one standard drink per hour. Consuming drinks faster than this rate causes alcohol to accumulate in your bloodstream.

Food Intake

Eating before or while drinking slows alcohol absorption:

Empty stomach: Alcohol absorbs in 15-30 minutes
With food: Alcohol absorbs in 30-90 minutes
Heavy meal: Can reduce peak BAC by 30-50%

Type of Alcohol

All alcoholic beverages are metabolized the same way once absorbed, but concentration matters:

Standard Drink Equivalents:

Beer (12 oz at 5% ABV): 0.6 oz pure alcohol
Wine (5 oz at 12% ABV): 0.6 oz pure alcohol
Distilled spirits (1.5 oz at 40% ABV): 0.6 oz pure alcohol

Individual Metabolism

Factors affecting metabolism rate:

Age: Metabolism slows with age
Liver health: Impaired liver function slows processing
Medications: Some drugs interact with alcohol metabolism
Genetics: Enzyme variations affect processing speed
Tolerance: Regular drinkers metabolize slightly faster

How Long Until You’re Sober?

Alcohol Elimination Rate

The average person eliminates alcohol at a rate of 0.015% BAC per hour. This rate is relatively constant and cannot be significantly accelerated.

Time to Zero BAC Examples

Starting BAC	Time to 0.00% BAC
0.02%	~1.5 hours
0.05%	~3.5 hours
0.08%	~5.5 hours
0.10%	~7 hours
0.15%	~10 hours
0.20%	~13.5 hours

Important: Even after your BAC returns to zero, you may still experience “hangover” effects that impair driving ability.

Common BAC Myths Debunked

Myth 1: Coffee Sobers You Up

Reality: Coffee might make you feel more alert, but it does not reduce your BAC. Only time can eliminate alcohol from your system.

Myth 2: Cold Showers Reduce BAC

Reality: Cold showers may wake you up temporarily but have no effect on alcohol metabolism or BAC levels.

Myth 3: Exercise Burns Off Alcohol

Reality: While exercise increases metabolism slightly, it does not significantly accelerate alcohol elimination. Exercise while intoxicated can also be dangerous.

Myth 4: Vomiting Lowers BAC

Reality: Once alcohol is absorbed into the bloodstream (15-30 minutes after consumption), vomiting cannot reduce BAC. It may only help if done immediately after drinking.

Myth 5: You Can “Handle Your Liquor”

Reality: Tolerance means you don’t feel as impaired, but your BAC remains the same. Your driving ability and judgment are still compromised regardless of how you feel.

Risks of High BAC Levels

Short-Term Risks

Accidents: Increased risk of falls, drowning, burns, and traffic accidents
Violence: Higher likelihood of assault or domestic violence
Risky behavior: Unprotected sex, dangerous decisions
Alcohol poisoning: Can be fatal without treatment
Blackouts: Memory loss of events while intoxicated

Long-Term Health Risks

Chronic heavy drinking can lead to:

Liver disease (cirrhosis, fatty liver, hepatitis)
Heart problems (cardiomyopathy, arrhythmias, high blood pressure)
Brain damage (memory loss, cognitive impairment)
Cancer (mouth, throat, esophagus, liver, breast)
Mental health issues (depression, anxiety)
Weakened immune system

Legal Consequences of DUI

License suspension or revocation
Heavy fines ($500 to $10,000+)
Jail time (especially for repeat offenses)
Criminal record
Increased insurance premiums
Ignition interlock device requirement
Community service
Mandatory alcohol education programs

Safe Drinking Guidelines

CDC Recommendations

Moderate drinking:

Women: Up to 1 drink per day
Men: Up to 2 drinks per day

Binge drinking (avoid):

Women: 4+ drinks within 2 hours
Men: 5+ drinks within 2 hours

When to Avoid Alcohol Completely

Pregnant or trying to conceive
Taking medications that interact with alcohol
Diagnosed with certain medical conditions
Under the legal drinking age (21 in the US)
Operating vehicles or machinery
Recovering from alcohol use disorder

Strategies for Responsible Drinking

Before Drinking

Eat a substantial meal: Slows alcohol absorption
Plan transportation: Arrange a designated driver or rideshare
Set a drink limit: Decide in advance how many drinks you’ll have
Hydrate: Drink water before you start drinking alcohol
Check medications: Verify no dangerous interactions

While Drinking

Pace yourself: No more than one drink per hour
Alternate with water: One water for every alcoholic drink
Avoid drinking games: Lead to rapid consumption
Know what you’re drinking: Be aware of alcohol content
Never leave drinks unattended: Protect against tampering
Stick to your limit: Don’t let others pressure you

After Drinking

Never drive: Use rideshare, taxi, or designated driver
Don’t let friends drive drunk: Take their keys if necessary
Eat food: May help with hangover prevention
Drink water: Combat dehydration
Sleep it off: Give your body time to process alcohol

Frequently Asked Questions

How accurate is this BAC calculator?

BAC calculators provide estimates within ±20% for most people. Individual variations in metabolism, body composition, food intake, and other factors can affect actual BAC. Use this calculator as a guideline only, not a determination of your ability to drive legally or safely.

What is a standard drink?

A standard drink contains approximately 0.6 oz (14 grams) of pure alcohol:

12 oz beer (5% ABV)
5 oz wine (12% ABV)
1.5 oz distilled spirits (40% ABV)

Mixed drinks and craft beers often contain more alcohol than standard drinks.

Can I speed up alcohol elimination?

No. Your liver metabolizes alcohol at a fixed rate (about 0.015% BAC per hour). Time is the only thing that reduces BAC. Coffee, exercise, cold showers, and other remedies do not accelerate this process.

Why do women have higher BAC than men?

Women typically have:

Lower body water percentage (52-55% vs 68% in men)
Less alcohol dehydrogenase enzyme in the stomach
Higher body fat percentage, which doesn’t absorb alcohol
Generally smaller body size

These factors mean women reach higher BAC levels when consuming the same amount of alcohol as men.

Is it safe to drive the morning after drinking?

Not necessarily. If you drank heavily the night before, you may still have a significant BAC in the morning. For example, if you stopped drinking at midnight with a BAC of 0.15%, you’d still be at 0.06% at 6:00 AM - potentially impaired and possibly illegal in some states.

What should I do if someone has alcohol poisoning?

Call 911 immediately if someone shows signs of alcohol poisoning:

Confusion or stupor
Vomiting
Seizures
Slow breathing (fewer than 8 breaths per minute)
Irregular breathing
Blue-tinged or pale skin
Low body temperature
Unconsciousness

While waiting for help:

Keep the person awake and sitting up
If unconscious, position them on their side to prevent choking
Stay with the person
Do not give them coffee or food
Do not try to make them vomit

Does drinking water between alcoholic drinks help?

Yes, drinking water helps with hydration and slows alcohol consumption, but it does not reduce BAC levels. Water dilutes alcohol in the stomach before absorption but cannot reduce alcohol already in the bloodstream.

Can medications affect my BAC?

Yes. Many medications interact with alcohol:

Antibiotics: Can increase side effects
Pain relievers: Increased risk of stomach bleeding and liver damage
Antidepressants: Enhanced sedation and impairment
Diabetes medications: Dangerous blood sugar changes
Sleep aids: Extreme drowsiness and respiratory depression

Always check with your doctor or pharmacist about alcohol interactions with your medications.

Conclusion

Understanding your BAC is crucial for making safe, responsible decisions about alcohol consumption and driving. This free BAC calculator provides estimates to help you gauge your level of intoxication, but remember that it’s not a substitute for professional breathalyzer testing or good judgment.

The safest choice is always to avoid driving after drinking any amount of alcohol. Plan ahead with designated drivers, rideshare services, or public transportation. Your life and the lives of others depend on it.

If you or someone you know struggles with alcohol use, resources are available:

SAMHSA National Helpline: 1-800-662-4357 (free, confidential, 24/7)
Alcoholics Anonymous: aa.org
National Institute on Alcohol Abuse and Alcoholism: niaaa.nih.gov

Medical Disclaimer: This calculator is for educational and informational purposes only. It does not constitute medical or legal advice. BAC estimates may vary significantly from actual values. Never rely on this calculator to determine if it’s safe or legal to drive. When in doubt, don’t drive. Always consult with healthcare professionals regarding alcohol use and health concerns.