Blood Alcohol Level Calculator

Estimate your Blood Alcohol Concentration (BAC) with our comprehensive calculator

Calculate BAC based on drinks, body weight, gender, and time elapsed

CRITICAL DISCLAIMER: This calculator provides ESTIMATES ONLY for informational purposes. BAC levels vary significantly between individuals. NEVER drive or operate machinery after drinking. Always use a designated driver or rideshare service. This tool is not a substitute for professional medical advice or legal guidance.

Blood Alcohol Concentration Calculator

Enter Your Information

Gender affects alcohol metabolism rate
lbs
180 lbs
Higher body weight generally lowers BAC
drinks
4 drinks
1 standard drink = 14g pure alcohol
%
5%
Beer: 4-6%, Wine: 12-14%, Liquor: 40-50%
hours
2 hours
Liver metabolizes ~0.015% BAC per hour
What's a Standard Drink?

• 12oz beer (5% ABV) • 5oz wine (12% ABV) • 1.5oz liquor (40% ABV)

Your Estimated BAC Results

Current Estimated BAC

0.06%

Impaired - Do not drive

BAC Level Interpretation
Sober (0.00-0.03%)
Mild Impairment (0.03-0.06%)
Impaired (0.06-0.10%)
Legally Intoxicated (0.08-0.15%)
High Risk (0.15%+)
Calculation Summary
Gender Male
Body Weight 180 lbs
Standard Drinks 4.0
Time Elapsed 2 hours
Estimated BAC 0.06%
Legal Limit: 0.08% BAC in all US states
Estimated Time to Sober (BAC = 0%)
5.3 hours from now

BAC Timeline Visualization

Your BAC Timeline

Start
0.10%
1 hour
0.09%
Now (2h)
0.06%
4 hours
0.03%
Sober
5.3h

Understanding Blood Alcohol Concentration (BAC)

Blood Alcohol Concentration (BAC) is a measure of the amount of alcohol in your bloodstream, expressed as a percentage. Understanding how BAC is calculated and what different levels mean can help you make safer decisions about alcohol consumption.

BAC Calculation Formula

This calculator uses a modified Widmark formula, which is widely accepted for estimating BAC:

BAC = (Standard Drinks × 14) / (Body Weight in lbs × Gender Factor) - (0.015 × Time)

Where:

  • Standard Drinks: Number of drinks consumed (1 drink = 14g pure alcohol)
  • Gender Factor: 0.68 for males, 0.55 for females (accounts for body water percentage differences)
  • Time: Hours since drinking began (liver metabolizes ~0.015% BAC per hour)

BAC Level Interpretation

Different BAC levels produce varying effects on the body and carry different legal implications:

BAC Range Effects Legal Status
0.00-0.03% Mood elevation, slight relaxation Legal to drive*
0.03-0.06% Reduced coordination, euphoria May be impaired
0.06-0.10% Speech slurred, judgment impaired Illegal to drive
0.10-0.15% Poor coordination, blurred vision DUI offense
0.15%+ Severe impairment, risk of alcohol poisoning Serious DUI

Example Calculation

Let's calculate an example for a 180 lb male:

  • Gender: Male (factor = 0.68)
  • Weight: 180 lbs
  • Drinks: 4 standard drinks (56g alcohol)
  • Time: 2 hours since drinking began
  • Calculation: (4 × 14) / (180 × 0.68) - (0.015 × 2)
  • Result: 56 / 122.4 - 0.03 = 0.457 - 0.03 = 0.427% BAC
Important Factors: BAC estimates vary based on metabolism, food consumption, medication use, tolerance, and individual biological factors. This calculator provides estimates only and should not be used to determine fitness to drive.

Frequently Asked Questions

How accurate is this blood alcohol calculator?

This calculator uses the Widmark formula, which is widely accepted for BAC estimation. However, accuracy varies significantly (typically ±20-30%) due to individual factors like metabolism, food consumption, medication use, tolerance, and biological variations. This tool provides estimates only and should never be used to determine fitness to drive. Always err on the side of caution and use a designated driver.

What is the legal BAC limit for driving in the US?

In all 50 US states, the legal BAC limit for drivers aged 21 and over is 0.08%. For commercial drivers, the limit is typically 0.04%, and for drivers under 21, many states have "zero tolerance" laws with limits as low as 0.00-0.02%. Some states have additional penalties for "enhanced" BAC levels (usually 0.15% or higher). Remember that impairment can begin well below the legal limit.

How long does alcohol stay in your system?

Alcohol metabolism follows a fairly consistent pattern for most people:

  • Metabolism Rate: The liver processes about 0.015% BAC per hour on average
  • Detection Times:
    • Breath: 12-24 hours
    • Blood: 12-24 hours
    • Urine: 12-48 hours (up to 80 hours for advanced tests)
    • Hair: Up to 90 days
  • Factors Affecting Metabolism: Age, liver health, genetics, food consumption, and medication use

Remember: "Time is the only thing that sobers you up" - coffee, cold showers, and food do not speed up alcohol metabolism.

Can I lower my BAC faster by drinking coffee or taking a cold shower?

No. This is a dangerous misconception. Only time lowers your BAC. The liver metabolizes alcohol at a fairly constant rate of about 0.015% BAC per hour. Coffee, cold showers, exercise, or eating food might make you feel more alert, but they do not speed up alcohol metabolism or lower your BAC. In fact, caffeine might make you feel less impaired while your BAC remains high, potentially leading to riskier decisions.

What should I do if I've been drinking?

Always plan ahead for safe transportation:

  1. Designated Driver: Plan for a sober driver before drinking begins
  2. Rideshare/Taxi: Use Uber, Lyft, or traditional taxi services
  3. Public Transportation: Use buses, trains, or subways where available
  4. Stay Overnight: Arrange to stay at a friend's place or nearby accommodation
  5. Wait It Out: Remember the "one hour per drink" rule as a minimum guideline

If you're hosting: Offer non-alcoholic drinks, stop serving alcohol well before the event ends, and never let guests drive impaired.

Safety Tips
  • Never drink and drive
  • Use a designated driver
  • Eat before drinking
  • Pace your drinks
  • Alternate with water
  • Know your limits