Quick BAC Estimator
Use this blood alcohol level calculator to estimate your Blood Alcohol Concentration (BAC) based on body weight, number of standard drinks, and time.
Important: This estimate is educational only and not legal or medical advice. Do not use it to decide whether to drive.
What this blood alcohol levels calculator does
This tool provides a practical estimate of your blood alcohol concentration (BAC), which is the percentage of alcohol in your bloodstream. A BAC of 0.08% means 0.08 grams of alcohol per 100 milliliters of blood. In many regions, 0.08% is the legal driving limit, but impairment begins well before that point.
The calculator is based on a simplified Widmark-style formula that uses:
- Biological sex (to estimate body water distribution),
- Body weight,
- Total standard drinks consumed,
- Time elapsed since drinking began.
How to use the calculator
Step-by-step
- Choose your biological sex.
- Enter your current body weight and unit (lb or kg).
- Enter the number of standard drinks consumed.
- Enter how many hours have passed since your first drink.
- Click Calculate BAC.
For reference, one U.S. standard drink contains about 0.6 fluid ounces of pure alcohol (roughly 14 grams). That is approximately one 12 oz beer (5% ABV), one 5 oz glass of wine (12% ABV), or one 1.5 oz shot of spirits (40% ABV).
Interpreting your estimated BAC
Your result includes an estimated BAC value and an impairment category. Typical interpretation ranges are:
- 0.000–0.029%: Subtle effects possible.
- 0.030–0.059%: Mild euphoria and reduced caution.
- 0.060–0.079%: Judgment and coordination noticeably impaired.
- 0.080–0.149%: Significant impairment; illegal to drive in many places.
- 0.150–0.299%: Major motor/cognitive impairment; high risk.
- 0.300%+: Potential medical emergency.
Why this is only an estimate
Real BAC can vary a lot person to person. This calculator cannot account for every biological and situational factor. Your actual BAC may be higher or lower based on:
- Food in your stomach,
- Drinking speed and beverage strength,
- Hydration and fatigue,
- Medications and health conditions,
- Individual metabolism and tolerance.
Also, tolerance can make you feel less impaired without reducing your BAC. Feeling “fine” is not a reliable safety test.
Common BAC questions
Can coffee lower BAC?
No. Caffeine may make you feel more alert, but it does not reduce blood alcohol concentration.
Can cold showers or water sober you up faster?
No. Time is the primary factor. The liver processes alcohol at a limited rate, often approximated around 0.015 BAC per hour, though this varies by person.
How long until alcohol is out of your system?
That depends on your peak BAC and personal metabolism. This calculator gives a rough time-to-zero estimate, but it is not guaranteed.
Safety reminder
If you have been drinking, the safest choice is simple: do not drive. Use a rideshare, taxi, public transit, or a sober friend. If someone shows signs of alcohol poisoning (confusion, vomiting, slowed breathing, unresponsiveness), seek emergency help immediately.