BAC Blood Alcohol Calculator
Use this blood alcohol content calculator to estimate your BAC based on drinks, body weight, biological sex, and time since your first drink. This is an estimate only, not a legal or medical determination.
What this BAC calculator estimates
This BAC blood alcohol calculator estimates your blood alcohol concentration (BAC) using a common Widmark-style equation. It considers the amount of alcohol consumed, your body weight, biological sex, and time elapsed for metabolism. If you are looking for a quick BAC by weight and gender estimate, this tool gives a practical starting point.
Remember: your actual BAC can vary because real human physiology is messy. Food intake, medications, hydration, health conditions, and drinking speed all matter.
Formula used in this blood alcohol content calculator
Step 1: Total alcohol consumed (in fluid ounces of pure alcohol)
Total alcohol (A) = drinks × drink size (fl oz) × (ABV / 100)
Step 2: Estimated BAC
BAC = ((A × 5.14) / (weight × r)) − (0.015 × hours)
- weight is in pounds
- r is an alcohol distribution ratio (0.73 male, 0.66 female)
- 0.015 is a common average elimination rate per hour
If the result is negative, the calculator shows 0.000% BAC.
How to read your estimated BAC result
- 0.000–0.019%: Minimal noticeable effects for most people
- 0.020–0.049%: Mild impairment in judgment and reaction time
- 0.050–0.079%: Clear impairment, reduced coordination
- 0.080–0.149%: Significant impairment; in many places 0.08% is the legal driving limit
- 0.150% and above: High risk of severe impairment and possible alcohol poisoning
Even below legal thresholds, driving ability can be impaired. The safest BAC for driving is always 0.00%.
What counts as a standard drink?
Many people underestimate alcohol intake. In the U.S., one standard drink contains roughly 14 grams of pure alcohol, which is approximately:
- 12 fl oz beer at 5% ABV
- 5 fl oz wine at 12% ABV
- 1.5 fl oz distilled spirits at 40% ABV
Craft beers, cocktails, and large pours can contain much more than one standard drink.
Why your real BAC may be different
Common variables
- Drinking on an empty stomach versus after a meal
- How quickly alcohol was consumed
- Body composition and metabolic differences
- Fatigue, stress, illness, and medication interactions
- Inaccurate drink size or ABV estimates
Because of these factors, no online BAC tool can replace a breathalyzer, blood test, or professional medical/legal assessment.
Frequently asked questions
Can coffee lower BAC?
No. Coffee may make you feel more awake, but it does not reduce blood alcohol concentration.
How long does it take to sober up?
On average, the body eliminates around 0.015% BAC per hour. This rate varies by person, so use the estimate cautiously.
Can I use this as legal proof?
No. This is an educational BAC estimate tool. It is not valid legal evidence and not a medical diagnosis.
Safety reminder
If you may be impaired, do not drive. Use a rideshare, call a friend, or stay where you are. If someone shows signs of alcohol poisoning (confusion, vomiting, slow/irregular breathing, passing out), seek emergency medical help immediately.