How do you calculate blood alcohol content?

BAC is calculated using the Widmark formula: BAC = (alcohol consumed in grams ÷ (body weight in grams × Widmark factor)) × 100 − (metabolism rate × hours). The Widmark factor is 0.68 for males and 0.55 for females. Our BAC calculator handles all the math — just enter your weight, gender, drinks, and time.

How long does it take to sober up?

Your body metabolizes alcohol at about 0.015% BAC per hour (roughly one standard drink per hour). At a BAC of 0.08%, it takes about 5.3 hours to reach 0.00%. At 0.15%, it takes about 10 hours. Our sobriety calculator shows your estimated time to reach 0.00% BAC based on your current level.

What is the legal BAC limit for driving?

In most US states, the legal BAC limit is 0.08% for drivers 21 and over. For commercial drivers, it's 0.04%. For drivers under 21, most states have zero-tolerance laws (0.00-0.02%). However, impairment begins well below the legal limit — even a BAC of 0.02% affects judgment and reaction time.

Does BAC differ between males and females?

Yes. Women generally reach higher BAC levels than men of the same weight after consuming the same amount of alcohol. This is because women typically have a higher percentage of body fat and lower percentage of body water. The Widmark factor accounts for this: 0.68 for males vs 0.55 for females.

What is a standard drink?

A standard drink contains about 14 grams (0.6 oz) of pure alcohol. This equals: 12 oz of regular beer (5% ABV), 5 oz of wine (12% ABV), or 1.5 oz of distilled spirits (40% ABV). Many drinks served at bars and restaurants contain more than one standard drink — a pint of craft IPA (7% ABV) is about 1.5 standard drinks.

Does eating food affect BAC?

Eating food before or while drinking slows alcohol absorption into the bloodstream, which can reduce peak BAC. However, food does not prevent intoxication — it only delays it. High-protein and fatty foods are most effective at slowing absorption. Drinking on an empty stomach leads to faster, higher BAC peaks.

Can coffee or water lower your BAC?

No. Coffee, water, cold showers, exercise, and fresh air do NOT reduce your BAC or speed up alcohol metabolism. Only time reduces BAC — your liver processes alcohol at a fixed rate of about 0.015% per hour. Water and food can help you feel better but won't make you sober faster.

How accurate is a BAC calculator?

BAC calculators provide estimates based on the Widmark formula and average metabolism rates. Actual BAC can vary significantly based on genetics, food intake, medications, liver health, hydration, and individual metabolism. These calculators should never be used to determine if you're safe to drive — when in doubt, don't drive.

BAC Calculator

Our BAC calculator uses the Widmark formula to estimate your blood alcohol content based on your body weight, biological sex, number and type of drinks consumed, and time since your first drink. It accounts for alcohol metabolism rate to show how your BAC changes over time and estimates when you'll be sober again. Remember: this is an estimate — actual BAC varies based on many factors including food intake, medications, and individual metabolism.

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calendar_today Updated: July 2025

auto_awesome AI Insights AI

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Biological Sex

Body Weight

lbs

Drink Type

Number of Drinks

Hours Since First Drink

0 hrs

hrs

12 hrs

Custom Drink Settings

ABV Override (%)

Size Override (oz)

Estimated BAC local_bar

0.000%

Sober

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Legal Status

Under 0.08% limit

Time to Sober

Sober now

Peak BAC

0.000%

Standard Drinks

Alcohol Calories

0 cal

BAC Level

0.00 0.05 0.08 0.15 0.20+

warning Disclaimer: This is an estimate only. Actual BAC varies based on many factors. Never use this to decide if you're safe to drive.

Input Values

Body Weight (lbs)

Biological Sex

Male

Female

Number of Drinks

Drink Type

Beer

Wine

Spirits

Cocktail

lightbulb Tips

•1 standard drink = 12oz beer, 5oz wine, 1.5oz spirits
•Body metabolizes ~1 drink per hour
•0.08% BAC = legal limit in most US states
•Only time lowers BAC — not coffee or water

How to Use This Calculator

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Enter Your Details

Input your body weight and select biological sex. These determine how your body distributes alcohol.

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Add Your Drinks

Enter the number and type of drinks consumed. Use preset drink types or customize ABV and serving size.

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Set Time Elapsed

Enter how long since your first drink. This accounts for alcohol your body has already metabolized.

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Review BAC Results

See your estimated BAC, impairment level, legal status, and time until sober. Remember: this is an estimate only.

The Formula

The Widmark formula is the standard method for estimating BAC. It calculates alcohol concentration based on the total alcohol consumed relative to body water content (which differs by sex). The metabolism rate (0.015/hr average) represents how fast your liver processes alcohol over time.

BAC = (Alcohol in grams / (Body weight in grams × r)) × 100 - (0.015 × hours)

lightbulb Variables Explained

Alcohol (g) Total grams of pure alcohol consumed = drinks × oz × ABV × 29.5735 × 0.789
Body weight (g) Body weight converted to grams
r Widmark factor: 0.68 for males, 0.55 for females
0.015 Average BAC metabolism rate per hour (range: 0.010-0.020)
hours Time elapsed since first drink

tips_and_updates Pro Tips

One 'standard drink' = 12 oz beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%)

Your body metabolizes about one standard drink per hour on average

Food slows alcohol absorption but doesn't prevent intoxication

BAC of 0.08% is the legal limit in most US states — but impairment starts well below that

Women generally reach higher BAC than men at the same weight due to lower body water content

Coffee, cold showers, and exercise do NOT lower your BAC — only time does

Medications can dramatically increase alcohol's effects even at low BAC levels

Calculate Your Blood Alcohol Content (BAC)

Our free BAC calculator estimates your blood alcohol content based on your weight, gender, number of drinks, and time elapsed. See your impairment level, legal driving status, and how long until you're completely sober.

Blood Alcohol Content Calculator

How high is your BAC after drinking? Use our blood alcohol content calculator to find out. Based on the Widmark formula, it accounts for your weight, biological sex, drink type, and time to give you an accurate estimate. Whether you had beer, wine, or spirits, our BAC calculator shows your current level and impairment status.

How Long Until Sober Calculator

Wondering how long until your BAC reaches 0.00%? Your liver metabolizes alcohol at approximately 0.015% per hour — about one standard drink per hour. Our sobriety calculator shows exactly how long it will take based on your current estimated BAC level, so you can plan ahead for when it's safe to drive.

BAC Calculator by Weight and Gender

Body weight and biological sex significantly affect BAC. A 120 lb woman will reach a much higher BAC than a 220 lb man after the same number of drinks. Our BAC calculator by weight uses sex-specific Widmark factors (0.68 male, 0.55 female) for more accurate results tailored to your body.

Frequently Asked Questions

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