Estimate Your Blood Alcohol (‰)
Use this alcohol promille calculator to estimate BAC in promille (‰). This is an educational estimate, not a legal or medical determination.
Drinks Consumed
What Is an Alcohol Promille Calculator?
An alcohol promille calculator estimates your blood alcohol concentration (BAC) in promille (‰), a unit commonly used in many countries. In simple terms, 1.0‰ means 1 gram of alcohol per kilogram of blood. The higher your value, the stronger the expected effects on coordination, reaction time, judgment, and overall safety.
This page uses a practical Widmark-style estimate. It combines the alcohol consumed, your body weight, a biological distribution factor, and elapsed time to estimate how much alcohol remains in your system.
How the Calculator Works
1) Convert drinks to grams of alcohol
For each beverage type, the calculator estimates pure alcohol grams with this idea:
- Alcohol grams = volume (ml) × ABV × 0.789
- ABV is entered as a percentage (for example, 5 for beer, 12 for wine, 40 for spirits).
- 0.789 is ethanol density in g/ml.
2) Estimate initial BAC in ‰
Initial BAC is approximated by dividing total alcohol grams by your body water distribution:
- BAC (‰) ≈ alcohol grams / (r × body weight in kg)
- Typical r values used: 0.68 (male), 0.55 (female), 0.615 (other midpoint).
3) Subtract metabolism over time
The body removes alcohol gradually. A common estimate is 0.15‰ per hour. Final estimate:
- Estimated BAC (‰) = Initial BAC − (0.15 × hours)
- Never below zero (values are floored at 0).
How to Use This BAC Calculator Correctly
- Enter your current body weight in kilograms.
- Select the biological sex option that best matches your physiology.
- Add beer, wine, and spirits amounts with ABV.
- If you already know pure alcohol grams from labels or tracking apps, add it to “Other Pure Alcohol”.
- Enter hours since the first drink.
- Click calculate and review both promille and estimated time to zero.
Understanding Your Result
The result includes:
- Estimated BAC in promille (‰)
- Approximate BAC in percent (%)
- Total grams of alcohol consumed
- Estimated time until BAC reaches 0.00‰
Keep in mind: legal driving limits vary by country and can be very low (or zero tolerance). Even below legal limits, impairment may still be significant.
Important Factors This Calculator Cannot Fully Capture
Any online alcohol calculator is an estimate. Real BAC can differ due to:
- Food intake (empty stomach vs full meal)
- Drinking speed and drink size accuracy
- Hydration, sleep, stress, and medication use
- Metabolic differences and liver health
- Age, body composition, and individual tolerance
Because of these variables, this tool should be used for awareness and planning only—not for making safety-critical decisions.
Alcohol Safety Checklist
- Plan transport before drinking (taxi, rideshare, public transit, designated driver).
- Alternate alcohol with water.
- Eat before and during drinking.
- Avoid mixing alcohol with sedatives or recreational drugs.
- If someone is confused, vomiting repeatedly, or difficult to wake, seek urgent medical help.
Frequently Asked Questions
Is this a legal BAC test?
No. Only certified breath or blood testing by authorities can provide legal evidence.
Can coffee or a cold shower sober me up?
No. Only time lowers BAC. Caffeine may reduce sleepiness but does not remove alcohol.
What is a “safe” BAC to drive?
The safest choice is always 0.00‰. Laws vary by location, but impairment can begin well before many legal thresholds.
Final Note
This alcohol promille calculator is designed to improve decision-making, not to justify risky behavior. If there is any uncertainty about your condition, choose the safer option and do not drive.