BAC Calculator
Calculate your blood alcohol content based on weight, gender, drinks consumed, and time elapsed. Know when it's safe to drive and understand alcohol's effects on your body.
Understanding Blood Alcohol Content
Blood Alcohol Content (BAC) is a measure of the amount of alcohol in your bloodstream, expressed as a percentage. Understanding your BAC helps you make informed decisions about driving, work, and personal safety. This calculator uses the scientifically-validated Widmark formula to estimate your BAC based on personal factors.
How BAC is Calculated
Our calculator uses the Widmark formula, the gold standard for BAC estimation:
BAC = (alcohol_grams ÷ (body_water × 10)) - (0.015 × hours) This formula accounts for:
- Total alcohol consumed: Based on drink type and quantity
- Body water distribution: Varies by weight and gender
- Metabolism rate: Your liver processes alcohol at ~0.015% per hour
- Time elapsed: Alcohol concentration decreases over time
Standard Drink Definitions
All standard drinks contain 14 grams of pure alcohol:
🍺 Beer
12 fl oz (355ml)
5% alcohol by volume
🍷 Wine
5 fl oz (148ml)
12% alcohol by volume
🥃 Spirits
1.5 fl oz (44ml)
40% alcohol by volume
BAC Levels and Effects
| BAC Level | Legal Status | Typical Effects | Impairment Level |
|---|---|---|---|
| 0.00-0.02% | Safe to Drive | No noticeable effects | None |
| 0.02-0.05% | Caution Advised | Mild relaxation, slight euphoria | Minimal |
| 0.05-0.08% | Impaired | Reduced coordination, judgment affected | Moderate |
| 0.08-0.15% | Illegal to Drive | Significant impairment, slurred speech | Severe |
| 0.15%+ | Dangerous | Severe intoxication, health risk | Extreme |
Factors Affecting BAC
Several factors influence how alcohol affects your body:
Body Composition
- Weight: Heavier people have more body water to dilute alcohol
- Gender: Women typically have less body water (55% vs 68% for men)
- Body fat: Higher body fat percentage means less water for dilution
Consumption Factors
- Drink strength: Mixed drinks often exceed standard drink measurements
- Rate of consumption: Fast drinking overwhelms metabolism
- Food intake: Food slows alcohol absorption by 15-25%
Individual Factors
- Age: Metabolism slows with age
- Medications: Many drugs interact with alcohol
- Health conditions: Liver disease affects alcohol processing
- Tolerance: Regular drinkers may feel less impaired but still have high BAC
Legal Limits Worldwide
BAC legal limits vary by country and driver type:
- Most countries: 0.08% for regular drivers
- Some European countries: 0.05% standard limit
- Commercial drivers: Often 0.04% or lower
- Underage drivers: Zero tolerance in many jurisdictions
Metabolism and Recovery
Your liver processes alcohol at a fixed rate regardless of BAC level:
- Average metabolism: 0.015% BAC per hour
- One standard drink takes approximately 1 hour to process
- Coffee, exercise, or cold showers do not speed up alcohol metabolism
- Only time eliminates alcohol from your system
Safety Guidelines
🚨 Critical Safety Rules
- Never drive if you've been drinking, regardless of calculated BAC
- Plan ahead for safe transportation before drinking
- Seek medical help immediately if BAC exceeds 0.25% or you feel dangerously ill
- This calculator is for education only -- not legal evidence
Common Misconceptions
- Myth: "I can drive because I feel fine" -- Fact: Impairment occurs before you notice it
- Myth: "Coffee sobers me up" -- Fact: Only time reduces BAC
- Myth: "Beer has less alcohol than wine" -- Fact: Standard drinks have equal alcohol content
- Myth: "I have high tolerance, so my BAC is lower" -- Fact: Tolerance affects feeling, not actual BAC
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Aggiornato Febbraio 2026 · Testati e verificati
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Frequently Asked Questions
What is BAC and how is it calculated?
BAC (Blood Alcohol Content) is the percentage of alcohol in your bloodstream. It's calculated using the Widmark formula, considering your weight, gender, number of drinks, and time elapsed since drinking began.
What BAC level is considered legally drunk?
In most countries, a BAC of 0.08% is the legal limit for driving. However, impairment can begin at much lower levels (0.02-0.05%), so it's always safest not to drive after drinking any alcohol.
How long does it take for alcohol to leave your system?
Your body metabolizes alcohol at approximately 0.015% BAC per hour. This means it takes about 1 hour to process one standard drink, but this varies based on individual factors.
Why does gender affect BAC calculation?
Women typically have a lower percentage of body water than men, which means alcohol becomes more concentrated in their blood. This biological difference is factored into the Widmark formula.
What counts as one standard drink?
A standard drink contains 14 grams of pure alcohol: 12 oz beer (5% ABV), 5 oz wine (12% ABV), or 1.5 oz spirits (40% ABV). Mixed drinks often contain more than one standard drink.
Can I speed up alcohol metabolism?
No. Coffee, cold showers, or exercise don't speed up alcohol metabolism. Only time allows your liver to process alcohol at its fixed rate of about 0.015% BAC per hour.
How accurate is this BAC calculator?
This calculator provides estimates based on the Widmark formula. Actual BAC can vary due to factors like food consumption, medications, and individual metabolism. Never rely solely on calculations to determine if you can drive.
What are the effects of different BAC levels?
At 0.02-0.05%: mild relaxation and slight impairment. At 0.05-0.08%: reduced coordination and judgment. At 0.08-0.15%: significant impairment. Above 0.15%: severe intoxication and potential danger.
Does food affect BAC?
Yes, food slows alcohol absorption, potentially reducing peak BAC by 15-25%. However, it doesn't eliminate alcohol or significantly change total metabolism time.
What should I do if my BAC is too high?
Wait for your body to metabolize the alcohol naturally. Stay hydrated, eat food, and never drive. If BAC exceeds 0.25% or you feel dangerously ill, seek medical attention immediately.
Can I use this calculator for legal purposes?
No. This calculator is for educational purposes only. BAC can only be accurately measured with proper breathalyzer or blood tests. Never use estimates to determine legal driving ability.
Why is my BAC higher than expected?
Factors like empty stomach, certain medications, illness, or drinks stronger than assumed can increase BAC. Mixed drinks often contain more alcohol than standard drinks.