BAC Calculator

Calculate your Blood Alcohol Content using the Widmark formula. See your current BAC level, when you'll be under the legal limit, and how long until you're fully sober. Updated .

Body Weight

Weight Unit

Sex

Affects Widmark factor (r): male 0.68, female 0.55

Hours Since First Drink

What did you drink?

Current BAC

0.000

g/dL blood alcohol content

Sober

0.000.040.080.120.16+

Under Legal Limit

—

0.08 in most US states

Fully Sober

—

BAC = 0.00

Standard Drinks

—

total consumed

Peak BAC

—

before metabolism

BAC Now

—

g/dL

Std Drinks

—

consumed

Legal Limit

—

hours away

Sober In

—

hours

Full BAC Breakdown

BAC affects everyone differently. These are general guidelines — individual response varies significantly based on tolerance, body composition, food intake, sleep, and medications.

BAC Level	Status	Effects	Driving

Legal limits vary by location: Most US states: 0.08 g/dL for adults 21+. Commercial drivers: 0.04. Under 21: 0.00–0.02 (zero tolerance). Utah: 0.05. Most of Europe: 0.05. UK: 0.08. Germany: 0.05. Japan: 0.03.

One standard drink in the US contains 14 grams of pure alcohol. All of these count as one standard drink — even though serving sizes vary widely.

Drink	Volume	ABV	Std Drinks	Notes
🍺 Regular Beer	12 oz	5%	1.0	Most domestic lagers
🍺 Light Beer	12 oz	4.2%	0.8	Bud Light, Miller Lite
🍺 Craft / IPA	12 oz	6.5%	1.3	Higher ABV = more
🍺 Strong Ale	12 oz	8.0%	1.6	Double IPA, stout
🍷 Wine (glass)	5 oz	12%	1.0	Standard restaurant pour
🍷 Wine (glass)	6 oz	12%	1.2	Generous pour
🍷 Wine (bottle)	25 oz	12%	5.0	Full 750ml bottle
🥃 Shot (80-proof)	1.5 oz	40%	1.0	Vodka, whiskey, rum
🥃 Shot (100-proof)	1.5 oz	50%	1.25	Some whiskeys, Everclear
🍹 Margarita	6 oz	~15%	~1.5	Varies by recipe
🍹 Long Island	8 oz	~22%	~2.5	Multiple spirits
🥂 Pina Colada	9 oz	~10%	~1.5	Plus sugar calories

💡 The 1-drink-per-hour myth: It takes about 1 hour for your body to eliminate one standard drink, but absorption continues for up to 90 minutes after your last drink. Your BAC can keep rising for over an hour after you stop drinking. Coffee, water, food, and sleep do not speed up alcohol metabolism — only time does.

BAC Calculator — Blood Alcohol Content Guide ()

Blood Alcohol Content (BAC) measures the concentration of alcohol in your bloodstream, expressed as grams of alcohol per deciliter of blood (g/dL). A BAC of 0.08 means there are 0.08 grams of alcohol per 100 milliliters of blood — the legal driving limit in most US states. Even at BAC levels below 0.08, alcohol significantly impairs reaction time, judgment, and coordination.

The Widmark Formula

This calculator uses the Widmark formula, the most widely used method for estimating BAC: BAC = (A × 5.14) / (W × r) − 0.015 × H, where A is ounces of alcohol consumed, W is body weight in pounds, r is the Widmark factor (0.73 for men, 0.66 for women), and H is hours since drinking began. The 0.015 represents the average BAC elimination rate per hour.

Factors That Affect BAC

BAC is influenced by more than just how many drinks you've had. Body weight is the most significant factor — a heavier person has more water in their body to dilute alcohol. Sex matters because women generally have a higher body fat percentage and lower water content, plus lower levels of alcohol dehydrogenase enzyme, leading to higher BAC per drink. Food dramatically slows alcohol absorption — drinking on an empty stomach can increase peak BAC by 50% compared to drinking after a meal. Time is the only way to reduce BAC — coffee, water, cold showers, and sleep do not speed metabolism.

BAC and Driving

BAC	US Legal Status	Driving Impairment	Approx. Standard Drinks*
0.02	Legal (except under 21)	Slight relaxation, altered mood	~1 drink
0.04	Legal (CDL limit for commercial)	Reduced vigilance, impaired tracking	~2 drinks
0.05	Illegal in Utah & most of Europe	Reduced coordination, impaired judgment	~2–3 drinks
0.08	Illegal in most US states	Significant impairment, 7× crash risk	~4 drinks
0.10	Illegal everywhere in US	Slurred speech, poor coordination	~5 drinks
0.15	Aggravated DUI in many states	Severe impairment, possible blackout	~7–8 drinks
0.20+	Illegal everywhere	Disorientation, nausea, loss of consciousness risk	~10+ drinks

*Approximate for a 160 lb male over 2 hours. Individual results vary significantly.

The legal limit is not the safe limit. Studies show that driving impairment begins at BAC 0.02 — well below the legal limit of 0.08. At 0.05 BAC, the risk of a crash doubles compared to sober driving. At 0.08, crash risk is 7 times higher. At 0.15, it is 25 times higher. The only safe amount of alcohol before driving is zero.

How is BAC calculated?

BAC is calculated using the Widmark formula: BAC = (Alcohol in grams × 100) / (Body weight in grams × Widmark factor) − (Elimination rate × Hours). The Widmark factor accounts for the proportion of body water that absorbs alcohol — 0.73 for men and 0.66 for women on average. The elimination rate is approximately 0.015 g/dL per hour for most people. This formula gives a reasonable estimate but cannot account for individual variation in metabolism, food consumption, hydration, or medications.

How long does alcohol stay in your system?

Alcohol is eliminated at approximately 0.015 BAC per hour — meaning if your BAC is 0.12, it will take about 8 hours to reach 0.00. This rate is relatively constant regardless of food, water, coffee, or exercise. A breathalyzer can detect alcohol for 12–24 hours after drinking. Blood tests can detect it for up to 24 hours. Urine tests can detect it for 24–72 hours. Hair follicle tests can detect alcohol metabolites for up to 90 days. The only thing that lowers BAC is time.

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

Women generally reach higher BAC than men of the same weight after drinking the same amount due to two factors. First, women typically have a higher percentage of body fat and lower percentage of water — since alcohol dissolves in water, less body water means higher concentration. Second, women have lower levels of alcohol dehydrogenase, the enzyme that begins metabolizing alcohol in the stomach before it reaches the bloodstream. The Widmark factor reflects this: 0.73 for men vs 0.66 for women on average.

Does food affect BAC?

Yes — significantly. Food in your stomach slows the absorption of alcohol into the bloodstream, lowering peak BAC and delaying when it's reached. A full meal can reduce peak BAC by up to 50% compared to drinking on an empty stomach. High-fat and high-protein foods are most effective at slowing absorption. However, food does not speed up alcohol elimination — it only slows absorption. Once alcohol is in your bloodstream, it is eliminated at the same constant rate regardless of what you eat or drink.

What is a standard drink?

In the United States, a standard drink contains 14 grams (0.6 fl oz) of pure ethanol. This equals: 12 oz of regular beer (5% ABV), 5 oz of wine (12% ABV), or 1.5 oz of distilled spirits (40% ABV / 80-proof). The key is that many drinks contain more than one standard drink — a craft IPA at 8% ABV in a 16 oz pint contains about 2.1 standard drinks, and a generous restaurant wine pour of 7 oz contains 1.4 standard drinks. Always check ABV and serving size.

Can you sober up faster with coffee or water?

No. Coffee, water, food, cold showers, exercise, and sleep do not speed up alcohol metabolism. Your liver processes alcohol at a fixed rate of approximately one standard drink per hour regardless of what else you consume. Coffee may make you feel more alert — "wide awake drunk" — but does not lower your BAC. Water helps prevent dehydration and may reduce hangover severity the next day, but it does not accelerate alcohol elimination. Time is the only reliable way to lower BAC.