BAC Calculator
Estimate your blood alcohol content based on drinks, weight, and time.
Do not use this calculator to decide whether you can drive. BAC estimates are approximate, alcohol affects people differently, and legal limits vary. If you have been drinking, arrange a safe ride.
Blood alcohol calculator
Enter your drinking details to estimate BAC using a Widmark-style calculation.
This is a population-based estimate and may not reflect individual body composition.
Drink sizes and alcohol percentages can differ.
Estimated BAC
0.038%
approx.Low estimated range
Subtle effects may begin. Impairment can occur before someone feels noticeably intoxicated.
2 hr 31 min
Based on a simple 0.015 BAC/hour elimination estimate.
2.0
Approximate U.S. standard drinks, based on 14 g alcohol each.
Personalized interpretation
Your estimated BAC is 0.038%, based on the values entered.
At this estimated range, coordination, judgment, attention, and reaction time may be impaired. Alcohol effects vary by person, and impairment can occur before reaching a legal limit.
BAC calculators cannot determine whether you are safe or legal to drive. If you have been drinking, the safest choice is to avoid driving.
BAC range and impairment guide
0.01%–0.03%
Subtle effects may begin
Mood, attention, and judgment may start to change, even if effects feel mild.
0.04%–0.06%
Judgment and coordination may be affected
Reaction time, decision-making, and coordination can become less reliable.
0.07%–0.09%
Reaction time may be significantly impaired
Driving ability and risk awareness may be reduced. Impairment can occur below legal limits.
0.10%–0.15%
Clear impairment risk
Balance, speech, reaction time, and judgment may be strongly affected.
0.16%+
High impairment risk
This range may indicate serious impairment and possible medical concern.
No BAC range should be considered “safe.” Legal limits vary by jurisdiction, and impairment can occur below legal limits.
What BAC means
How BAC is estimated
Many blood alcohol calculators use variants of the Widmark equation. This page estimates BAC from alcohol consumed, body weight, a sex-based body water distribution factor, time since drinking, and an estimated elimination rate.
The estimate is population-based and approximate. It is not a medical test, breath test, blood test, or legal measurement.
Factors that affect BAC
Why BAC calculators are limited
- • Self-reported drinks can be inaccurate.
- • Pour sizes and alcohol percentages vary.
- • Alcohol absorption differs by person.
- • Legal or medical BAC requires proper testing.
- • BAC does not fully measure impairment.
- • Estimates should not guide driving decisions.
Safety and legal considerations
Legal limits vary by country, state, age, license type, and driver category. Some drivers may have zero-tolerance rules. This calculator is not legal advice.
Impairment can happen below legal limits. The safest option after drinking is not to drive. Use a designated driver, taxi, rideshare, public transit, or stay overnight.
BAC formula explanation
Estimated BAC ≈ (Alcohol consumed ÷ (Body weight × Distribution factor)) − Metabolism adjustmentMetabolism adjustment ≈ Elimination rate × Hours since drinkingAlcohol consumed is estimated from drink count, drink size, and ABV. Body weight and distribution factor approximate how alcohol is distributed in body water. Time since drinking is used to subtract a simple elimination estimate. This formula is not exact and should not be treated as clinically or legally definitive.
Medical urgency: If someone is unconscious, cannot be awakened, breathing slowly or irregularly, vomiting repeatedly, or showing signs of alcohol poisoning, seek emergency medical help immediately.
Frequently Asked Questions
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