πΊ Blood Alcohol Content (BAC) Calculator
Estimate your blood alcohol level based on drinks consumed, body weight, gender, and time since drinking.
β οΈ
Quick answer:
This BAC calculator uses the Widmark formula to estimate your blood alcohol content in percent. In many places, a BAC of 0.08% or higher is the legal limit for driving, but impairment can begin at much lower levels. Use this result for education only β never to decide whether it is safe or legal to drive.
How to use this BAC calculator
- Enter how many standard drinks you have consumed.
- Add your body weight and select kilograms or pounds.
- Choose your biological sex so the distribution ratio can be applied.
- Enter the number of hours since your first drink.
- Press Estimate My BAC and review the numeric result and safety message.
This tool gives you a quick estimate of your current BAC, but it cannot account for every factor that affects how your body processes alcohol.
Widmark Formula
The calculator is based on the Widmark formula: BAC = (A Γ· (W Γ r)) β (Ξ² Γ t)
- A β alcohol consumed in grams (1 standard drink β 14 g).
- W β body weight in grams.
- r β distribution ratio (β 0.68 for males, 0.55 for females).
- Ξ² β average metabolism rate (β 0.015% BAC per hour).
- t β hours since your first drink.
The tool first converts your total drinks into grams of alcohol, scales by your body weight and distribution ratio, and then subtracts the amount of alcohol your body is likely to have metabolized over time.
Worked BAC examples
These simple examples show how the calculator behaves in typical situations.
- Example 1: A 70 kg male, 3 standard drinks over 2 hours The estimated BAC is around the 0.05β0.06% range, where mild impairment and slower reactions begin.
- Example 2: A 60 kg female, 4 standard drinks over 1 hour The estimated BAC can exceed 0.08%, which is above the legal driving limit in many places and considered legally impaired.
- Example 3: A 90 kg male, 2 standard drinks over 3 hours The estimated BAC may stay below 0.03%, but there can still be subtle effects on judgment and reaction time.
BAC effect reference
| BAC Level | Typical Effects |
|---|---|
| 0.00β0.02% | Little to no effect |
| 0.02β0.05% | Relaxation, mild impairment |
| 0.06β0.08% | Mild impairment of balance and speech |
| 0.08β0.15% | Legally impaired in most countries; significant impairment |
| 0.15β0.30% | Severe impairment; vomiting risk |
| > 0.30% | Life-threatening; loss of consciousness |
β οΈ Important: Never drink and drive. This calculator provides estimates only. Actual BAC varies by individual. If you feel impaired, do not operate a vehicle. In most countries, the legal driving limit is 0.08% BAC.
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Frequently asked questions
This BAC calculator uses the Widmark formula with standard assumptions about alcohol distribution and metabolism. It gives a reasonable estimate for many adults, but real BAC is affected by age, health, medications, food intake, and individual metabolism. It must not be used to decide whether it is safe or legal to drive.
No. This tool is for education only and cannot guarantee whether you are safe or legal to drive. Alcohol affects everyone differently, and legal limits vary by country and state. If you have been drinking at all, the safest choice is not to drive and to use a taxi, ride share, or designated driver instead.
A BAC of 0.08% means there are 0.08 grams of alcohol per 100 milliliters of blood. In many countries and US states, 0.08% is the legal limit for driving. At or above this level, most people will have clearly impaired judgment, reaction time, and coordination.
Most people metabolize alcohol at about 0.015% BAC per hour, but the rate can be slower or faster depending on body size, liver health, medications, and other factors. There is no safe way to speed this up with coffee, cold showers, or exercise; only time lowers your BAC.
The calculator uses different distribution ratios for males and females, but it still relies on averages. Individual BAC can differ for people with higher or lower body fat, certain medical conditions, or who are taking medications. Always treat the result as an estimate, not a measurement.
No. This BAC calculator is for informational and educational purposes only and is not medical, legal, or safety advice. It does not replace guidance from a doctor, lawyer, or local authorities. Never make decisions about driving, working, or health treatment based solely on this tool.
Sources and disclaimers
- Widmark, E. M. P. βPrinciples and Applications of Medicolegal Alcohol Determination.β
- Centers for Disease Control and Prevention (CDC) guidance on alcohol and health.
- Local traffic safety and drink-driving regulations for your country or state.
Disclaimer: This calculator is for informational and educational purposes only and does not provide medical, legal, or safety advice. Do not use it to decide whether it is safe or legal to drive.
Last reviewed: March 2026