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Blood Alcohol Calculator

Estimate your blood alcohol content (BAC) based on drinks, weight, gender, and time. Understand impairment levels.

BAC Worksheet
Disclaimer: This is an estimate only. Do not drink and drive. Individual metabolism varies.

Understanding Blood Alcohol Content

BAC measures how much alcohol is in your blood. It's affected by how much you drink, your weight, gender, and time.

Important: This is an estimate only. Individual metabolism varies. Never drink and drive.

BAC Impairment Levels

  • 0.02-0.03%: Slight relaxation, mild mood changes
  • 0.05-0.06%: Lowered inhibitions, impaired judgment
  • 0.08%: Legal limit - impaired coordination, reaction time
  • 0.10-0.12%: Significant impairment, slurred speech
  • 0.15%+: Major impairment, risk of blackout

Standard Drink Sizes

  • 12 oz regular beer (5% alcohol)
  • 5 oz wine (12% alcohol)
  • 1.5 oz spirits (40% alcohol)
  • 8-9 oz malt liquor (7% alcohol)

Factors Affecting BAC

  • Body weight: Lower weight means higher BAC from the same number of drinks — alcohol is distributed through body water
  • Biological sex: Women typically reach higher BAC from the same drinks due to lower body water percentage and different enzyme levels
  • Food: Eating before or while drinking slows absorption significantly. A full stomach can reduce peak BAC by up to 50%
  • Drinking speed: Faster consumption produces higher peak BAC. The body eliminates alcohol at a fixed rate (~0.015%/hour) regardless of how much you consume
  • Drink strength: Craft beers (7-12% ABV), strong cocktails, and wines vary widely from standard drink assumptions

How Long to Sober Up

The body metabolizes approximately 0.015% BAC per hour — roughly one standard drink per hour. There is no way to speed this up. Coffee, cold showers, and food do not lower BAC faster; only time works.

  • BAC of 0.08% → approximately 5.3 hours to reach 0.00%
  • BAC of 0.12% → approximately 8 hours to reach 0.00%
  • BAC of 0.15% → approximately 10 hours to reach 0.00%

These are estimates. Sleep does not accelerate metabolism — you can still be legally impaired the morning after heavy drinking.

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Frequently Asked Questions

What is BAC?

Blood Alcohol Content - the percentage of alcohol in your bloodstream. 0.08% is the legal limit for driving in most US states.

How is BAC calculated?

Using the Widmark formula: BAC = (Alcohol consumed × 5.14 / Weight × Gender constant) - (0.015 × hours)

How long does it take to sober up?

The body eliminates about 0.015% BAC per hour. There is no way to speed this up - only time works.

What counts as one standard drink?

12oz beer (5%), 5oz wine (12%), 1.5oz spirits (40%). All contain about 14g of pure alcohol.

Does drinking water lower BAC?

No. Drinking water does not lower BAC or speed up alcohol metabolism. Water can help prevent dehydration and reduce some hangover symptoms, but only time reduces BAC at the fixed rate of roughly 0.015% per hour.

Why do women typically reach higher BAC than men from the same drinks?

Women generally have a lower percentage of body water and higher body fat, so alcohol distributes through a smaller volume of water. Women also tend to produce less alcohol dehydrogenase, an enzyme that begins breaking down alcohol in the stomach before it reaches the bloodstream.

How does eating before drinking affect BAC?

Food in the stomach slows alcohol absorption into the bloodstream, lowering peak BAC and delaying the time it takes to reach that peak. A large meal before drinking can reduce peak BAC by roughly 30 to 50 percent compared to drinking on an empty stomach.

Is there a BAC level that is safe to drive?

No BAC level is established as fully safe for driving. Impairment to judgment and reaction time begins at very low levels, well below most legal limits. Legal thresholds vary by country and driver category. This calculator is for educational purposes and is not a guide to operating a vehicle.