BAC Calculator: Estimate Your Blood Alcohol Content
A 180 lb male who drinks 3 standard beers (12 oz, 5% ABV) over 2 hours has an estimated BAC of approximately 0.053%. The legal driving limit in all US states is 0.08%. One standard drink raises BAC by approximately 0.02-0.03% depending on body weight. WARNING: This is only an estimate. NEVER drink a...
Estimate Your BAC
Based on the Widmark formula. This is an ESTIMATE ONLY.
Estimated BAC
0.000%
Below legal limit
BAC Levels and Effects
| BAC % | Typical Effects | Legal Status | |||||
|---|---|---|---|---|---|---|---|
| 0.02% | Slight lightheadedness, relaxation | Legal in all states | |||||
| 0.05% | Lowered inhibitions, impaired judgment | Legal (but impaired) | |||||
| 0.08% | Reduced coordination, poor judgment | ILLEGAL to drive (all US states) | |||||
| 0.10% | Slurred speech, poor balance | Significantly impaired | |||||
| 0.15% | Severe impairment, possible blackout | Dangerous | |||||
| 0.20% | Disorientation, nausea | Very dangerous | |||||
| 0.30%+ | Loss of consciousness, risk of death | Medical emergency | What Is a Standard Drink? | Drink Type | Volume | ABV | Standard Drinks |
| Regular beer | 12 oz | 5% | 1.0 | ||||
| Light beer | 12 oz | 4.2% | 0.84 | ||||
| IPA / Craft beer | 12 oz | 7% | 1.4 | ||||
| Wine | 5 oz | 12% | 1.0 | ||||
| Spirits (shot) | 1.5 oz | 40% | 1.0 | ||||
| Cocktail (mixed) | Varies | Varies | 1.0-2.5 |
How Your Body Processes Alcohol
Your liver metabolizes alcohol at a roughly constant rate of about 0.015% BAC per hour (approximately one standard drink). You cannot speed this process up with coffee, cold showers, or exercise. The only way to lower your BAC is time.
Frequently Asked Questions
How is BAC calculated?
BAC is estimated using the Widmark formula: BAC = (alcohol_consumed_grams / (body_weight_grams x Widmark_factor)) - (0.015 x hours_since_first_drink). The Widmark factor is 0.68 for males and 0.55 for females, reflecting differences in body water content.
How long does it take for BAC to reach zero?
Your body eliminates alcohol at approximately 0.015% BAC per hour. After reaching a BAC of 0.08%, it takes about 5.3 hours to return to 0.00%. After a heavy night of drinking (BAC 0.15%), it can take 10+ hours. You may still be over the legal limit the morning after heavy drinking.
Does eating food lower your BAC?
Eating food before or while drinking slows alcohol absorption, resulting in a lower peak BAC. However, food does not remove alcohol already in your bloodstream. Eating after drinking has minimal effect on BAC. High-fat and high-protein meals slow absorption most effectively.
Is this calculator accurate enough to determine if I can drive?
NO. This calculator provides a rough mathematical estimate only. Actual BAC varies based on many factors this calculator cannot account for, including medications, liver health, genetics, hydration, and food intake. The only safe approach: if you have been drinking, do not drive. Use a rideshare, taxi, or designated driver.
What is the legal BAC limit?
In all 50 US states, the legal BAC limit for drivers 21+ is 0.08%. For commercial drivers, it is 0.04%. For drivers under 21, most states enforce zero tolerance (0.00-0.02%). Many countries have lower limits than the US — in much of Europe, the limit is 0.05%.