Educational estimate only. This blood alcohol content calculator is not legal or medical advice. Individual alcohol metabolism varies, and you should never drive after drinking.
What this estimated BAC calculator does
This tool provides a quick estimate of your blood alcohol concentration (BAC) using a widely known Widmark-style formula. It uses your body weight, biological sex factor, number of standard drinks, and elapsed time since your first drink to estimate current alcohol concentration in your blood.
Keywords people often search for include blood alcohol content calculator, BAC chart, DUI limit calculator, and drinking impairment estimator. This page aims to give a practical, understandable starting point for all of those topics.
How to use the calculator correctly
1) Count standard drinks, not just “glasses”
A standard drink in the U.S. is roughly 14 grams (0.6 fl oz) of pure alcohol. Typical examples:
- 12 oz beer at 5% ABV
- 5 oz wine at 12% ABV
- 1.5 oz distilled spirits at 40% ABV
If your drink is larger or stronger than the examples above, it may count as more than one standard drink.
2) Enter realistic timing
The calculator subtracts alcohol metabolism over time. Enter the number of hours since your first drink in the session. If timing is uncertain, round conservatively and assume your BAC may be higher than estimated.
How the BAC estimate is calculated
The estimate uses this simplified structure:
- A = total alcohol in fluid ounces (standard drinks × 0.6)
- W = body weight in pounds
- r = Widmark body-water constant (sex-based estimate)
- H = hours since first drink
Estimated BAC = (A × 5.14 / (W × r)) − (0.015 × H)
The 0.015 term reflects an average elimination rate per hour. Real elimination can vary by person, health, meal timing, hydration, medication interactions, and genetics.
Interpreting your result
General impairment ranges
- 0.00–0.019: Subtle effects may begin.
- 0.02–0.049: Reduced inhibition and divided-attention decline.
- 0.05–0.079: Noticeable coordination and reaction impairment.
- 0.08+: Illegal for driving in many jurisdictions; significant impairment risk.
- 0.15+: Severe impairment and increased danger.
Legal limits depend on location and context (commercial drivers, underage laws, zero-tolerance rules, and more). Never rely on an estimate alone to make safety decisions.
Important limitations of any BAC calculator
- Absorption is not instant; BAC can continue rising after your last drink.
- Food can delay peak BAC but not eliminate impairment.
- Body composition, hormones, and medications can materially alter outcomes.
- Fatigue and stress can worsen driving performance even at lower BAC levels.
Safety-first guidance
If you drank alcohol, the safest rule is simple: do not drive. Use a designated driver, rideshare, taxi, or public transit. If someone appears dangerously intoxicated, stay with them and seek medical help when needed.
Frequently asked questions
Is this BAC calculator accurate?
It is a rough estimate useful for education and awareness. It is not a substitute for a calibrated breathalyzer, clinical testing, or legal determination.
Can coffee or a cold shower lower BAC faster?
No. Caffeine may make you feel more awake, but it does not speed alcohol elimination. Time is the main factor.
Why can two people with the same drinks have different BAC?
Differences in weight, body water distribution, metabolism, food intake, medication use, and drinking pace all matter.