Free BAC Calculator - Blood Alcohol Content Estimator
Estimate your blood alcohol content based on drinks consumed. Best free BAC calculator 2025 - understand alcohol effects and make safe choices.
Quick Answer
BAC (Blood Alcohol Content) is estimated using the Widmark formula: BAC = (Alcohol consumed in grams / (Body weight × r)) - (Time × 0.015), where r is 0.68 for men, 0.55 for women. The legal limit for driving in most US states is 0.08%. This calculator provides estimates only - actual BAC varies by many factors. Calculate at practicalwebtools.com.
Key Facts about BAC Calculator:
- Legal driving limit in US: 0.08% BAC (lower in some states)
- Body processes approximately 0.015% BAC per hour
- BAC affected by: weight, gender, food, metabolism, drink strength
- Standard drink: 12oz beer, 5oz wine, 1.5oz spirits
- 0.02-0.03%: mild relaxation; 0.08%: impaired driving; 0.30%+: dangerous
- Women typically reach higher BAC than men at same consumption
- Food slows alcohol absorption but does not prevent intoxication
Why Use Our BAC Calculator?
Estimate your BAC:
BAC Estimation
Calculate blood alcohol level.
Time Factor
See how BAC decreases over time.
Impairment Level
Understand effects at your BAC.
Driving Advisory
Know when you may be safe to drive.
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How to BAC Calculator in 3 Easy Steps
Estimate your BAC:
Enter Details
Weight, gender, drinks consumed.
Add Time
Hours since first drink.
See Estimate
View estimated BAC and effects.
Make Safe Choices
Understand your approximate intoxication level
Plan safe transportation
Know when alcohol effects wear off
Make informed drinking decisions
Common Use Cases for BAC Calculator
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Frequently Asked Questions
Everything you need to know about our bac calculator
How is BAC calculated?
Widmark formula using drinks, weight, gender, time - estimates only.
Widmark formula considers alcohol grams, body weight, gender factor, and time elapsed. It provides estimates; actual BAC varies by many individual factors.
What BAC is legally drunk?
0.08% in most US states; lower for commercial drivers and under-21.
In most US states, 0.08% BAC is the legal limit for driving. Some states have lower limits (0.05%). Commercial drivers: 0.04%. Under 21: often zero tolerance.
How long until I am sober?
About 0.015%/hour. From 0.08%, approximately 5-6 hours to zero.
The body eliminates about 0.015% BAC per hour. At 0.08%, it takes approximately 5-6 hours to reach 0%. Time is the only thing that lowers BAC.
Does coffee or water lower BAC?
No - nothing but time lowers BAC. Coffee only masks impairment.
No. Coffee may make you feel more alert but does not lower BAC. Water helps hydration but does not speed alcohol metabolism. Only time reduces BAC.
Still have questions? Try the tool yourself!
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