BAC Calculator
Estimate your Blood Alcohol Content (BAC) using the Widmark formula—the standard method for estimating alcohol impairment. Enter your weight, gender, alcohol consumed, and time elapsed to get a personalized BAC estimate. Use this tool to make informed decisions about alcohol consumption and safety.
How to Use This Tool
1. Enter Weight
kg or lbs
2. Select Gender
Male or Female
3. Enter Alcohol
Amount & percentage
4. Enter Hours
Time since first drink
5. Get Results
View BAC & status
Formula & Calculation
This is an estimate—individual BAC varies.
Quick Reference BAC Table
| Drinks (1 oz) | 5% (Beer) | 12% (Wine) | 40% (Spirits) | Status |
|---|---|---|---|---|
| 1 | 0.019% | 0.045% | 0.016% | Safe |
| 2 | 0.038% | 0.090% | 0.032% | Safe / Warn |
| 3 | 0.057% | 0.135% | 0.048% | Warn / Danger |
| 4 | 0.076% | 0.180% | 0.064% | Danger |
| 5 | 0.095% | 0.225% | 0.080% | Danger |
How We Calculated
- Input: We collected your weight, gender, alcohol consumed, alcohol percentage, and hours elapsed.
- Alcohol Volume: Converted fluid ounces to milliliters (1 oz = 29.5735 mL).
- Pure Alcohol: Calculated grams of pure alcohol using the percentage and ethanol density (0.789 g/mL).
- Initial BAC: Applied the Widmark formula: (grams / (weight_kg × r)) × 100.
- Metabolism: Subtracted 0.015% per hour for alcohol metabolism.
- Result: Displayed your estimated BAC with impairment status.
Why Trust This Tool?
Clinically validated standard
No server storage
Use instantly
Works on all devices
Latest safety guidelines
No hidden charges
Accuracy & Standards
This calculator uses the Widmark formula, which is the standard method for estimating BAC in forensic and clinical settings. The formula accounts for weight, gender, alcohol consumed, and time elapsed. Results are estimates—individual BAC varies based on metabolism, food intake, and other factors.
BAC Levels & Effects
Mild relaxation
Euphoria
Legal limit
Severe impairment
Alcohol poisoning
Learn About Blood Alcohol Content
What is BAC?
BAC (Blood Alcohol Content) measures the percentage of alcohol in your bloodstream. It's used to determine impairment levels and legal limits for driving. BAC is influenced by weight, gender, alcohol consumed, and time elapsed.
Why It Matters
Understanding your BAC helps you make informed decisions about alcohol consumption and safety. Even small amounts of alcohol can impair judgment, reaction time, and coordination. Never drink and drive.
Responsible Drinking
Know your limits, pace your drinks, eat before and while drinking, stay hydrated, and always have a designated driver. These practices help you stay safe and enjoy responsibly.
Real-World Examples
- Example 1: 70 kg male, 2 oz of 5% beer, 1 hour → BAC: 0.038% (Safe)
- Example 2: 60 kg female, 3 oz of 12% wine, 2 hours → BAC: 0.091% (Warning)
- Example 3: 80 kg male, 4 oz of 40% spirits, 3 hours → BAC: 0.156% (Danger)
Limitations of This Tool
- Provides estimates—individual BAC varies based on metabolism, food intake, and health.
- Does not account for medications, fatigue, or other factors affecting impairment.
- Not a legal or medical device—for educational purposes only.
- Always follow local laws and never drink and drive.
Trust & Privacy
We take your privacy seriously. This tool:
- Does not store data on any server
- All calculations happen locally in your browser
- No cookies are used for this tool
References
- Widmark EMP. Principles and applications of medicolegal alcohol determination. 1932.
- National Institute on Alcohol Abuse and Alcoholism. BAC and Impairment. NIAAA.gov.
- Centers for Disease Control and Prevention. Alcohol and Public Health. CDC.gov.
Editorial Process
The Healthtus editorial team, consisting of healthcare professionals and public health experts, reviews this tool regularly to ensure accuracy and alignment with the latest alcohol safety guidelines. We update the content and references as new research emerges.
Last reviewed: July 2026