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BAC Calculator

Estimate blood alcohol content based on drinks, weight, and time.

Last updated: June 13, 2026

Calculator

Number of Drinks

Body Weight

lbs

Gender

Hours Drinking

Results

Estimated BAC0.045%

Minimal effects

StatusMinimal effects

Legal Limit (US)0.08%

You are under the limit

DisclaimerEstimate only - do not drink and drive

How to Use This Calculator

1Enter the number of standard drinks consumed.
2Enter your body weight.
3Select your gender.
4Enter hours spent drinking.
5View estimated BAC and impairment level.

Formula Explanation

BAC is estimated using the Widmark formula, which accounts for alcohol consumed, body weight, gender-specific water ratio, and time-based metabolism.

BAC = (Alcohol oz x 5.14) / (Weight x Gender Ratio) - 0.015 x Hours

Variables:

DrinksStandard drinks (12oz beer, 5oz wine, 1.5oz liquor)

WeightBody weight in pounds

Gender RatioMale: 0.73, Female: 0.66

HoursTime spent drinking

Worked Examples

3 drinks, 170 lbs, male, 2 hours

1. Alcohol: 3 x 0.6 oz = 1.8 oz
2. BAC = (1.8 x 5.14) / (170 x 0.73) - 0.015 x 2
3. = 0.075 - 0.030 = 0.045

Result: BAC: 0.045% - under the legal limit but mildly impaired

Why Use This Calculator

Know your estimated impairment level.
Understand the legal limit in context.
See how time reduces BAC.
Make safer decisions about driving.

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Tips & Best Practices

One standard drink raises BAC by roughly 0.02-0.03%.
Your body metabolizes about one drink per hour.
Food slows absorption but does not prevent it.
The legal limit in all US states is 0.08% BAC.

Common Mistakes to Avoid

❌ Thinking coffee or food sobers you up quickly.

✅ Only time reduces BAC. Coffee makes you an alert drunk, and food slows absorption but does not speed elimination.

❌ Assuming you are fine at 0.05% BAC.

✅ Impairment begins at 0.02% BAC. Even below the legal limit, reaction time and judgment are affected.

Frequently Asked Questions

How many drinks to reach 0.08% BAC?

Varies greatly by weight, gender, and time. A 170-lb male reaches 0.08% after about 4 drinks in 1 hour. A 130-lb female may reach it after 2-3 drinks in the same time.

How long does it take BAC to reach 0?

The body eliminates alcohol at about 0.015% per hour. From 0.08%, it takes about 5.3 hours to reach 0.00%. There is no way to speed this up.

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Embed This Calculator

Add the BAC Calculator to your website for free. Copy the code below and paste it into your HTML.

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<iframe src="https://redicalc.com/embed/fitness/bac-calculator" width="100%" height="600" style="border:none;border-radius:12px;box-shadow:0 1px 3px rgba(0,0,0,0.1);" title="BAC Calculator — RediCalc.com" loading="lazy" allowtransparency="true"></iframe>

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Disclaimer: This calculator is provided for informational and educational purposes only. Results are estimates and should not be used as a substitute for professional advice. RediCalc.com makes no guarantees regarding the accuracy, completeness, or suitability of any calculations. Always consult a qualified professional before making financial, health, construction, or other important decisions.

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