Estimate your Blood Alcohol Content (BAC) from your sex, body weight, the time since your first drink, and what you drank. The calculator uses the Widmark formula. Results are an estimate for educational purposes only.
The BAC calculator on this page estimates your Blood Alcohol Content (BAC) — the percentage of alcohol in your bloodstream — based on your sex, body weight, how long ago you started drinking, and exactly what you drank. Enter your beers, wines, shots of liquor, or any other drink, and the calculator uses the well-known Widmark formula to estimate your current BAC, how long until it returns to zero, and what level of impairment that BAC typically corresponds to. It is a fast way to understand roughly where you stand after drinking.
Important: This calculator provides an estimate only. Many personal and situational factors affect real BAC, and the only way to know your true level is a breathalyzer or blood test. Never rely on a calculator to decide whether it is safe or legal to drive. When in doubt, do not drive.
Blood Alcohol Content, also called Blood Alcohol Concentration, is a measure of how much alcohol is present in your blood, expressed as a percentage by volume. A BAC of 0.08% — the legal driving limit for adults in most of the United States and many other countries — means that 0.08% of your blood, by volume, is alcohol. BAC rises as you drink and your body absorbs alcohol, peaks some time after your last drink, and then falls steadily as your liver metabolizes the alcohol. Because the liver processes alcohol at a roughly constant rate, the only thing that reliably lowers your BAC is time. Coffee, cold showers, food, and water do not speed up the elimination of alcohol already in your bloodstream.
Using the calculator takes only a few seconds:
Click Calculate and the tool reports your estimated current BAC, how many more hours until it reaches 0%, and a description of the typical effects at that level. A chart shows how your BAC declines over time.
This calculator is based on the Widmark formula, developed by Swedish researcher Erik Widmark in the early 20th century and still the foundation of most BAC estimation today. In its basic form:
BAC = (A / (W × r)) × 100 − (β × t)
Where A is the mass of pure alcohol consumed (in grams), W is body weight (in grams), r is the alcohol distribution ratio (a constant that differs between men and women), β is the elimination rate (the speed at which the body clears alcohol, about 0.015% per hour), and t is the time in hours since drinking began. The mass of alcohol in a drink is found by multiplying its volume by its ABV and by the density of ethanol (about 0.789 g/ml). For example, a 12 oz (355 ml) beer at 5% ABV contains roughly 355 × 0.05 × 0.789 ≈ 14 grams of pure alcohol — the standard "one drink" in the United States.
When you drink, alcohol is absorbed through the lining of your stomach and small intestine into your bloodstream. Absorption is relatively fast, especially on an empty stomach, which is why BAC can climb quickly. Once in the blood, alcohol is distributed throughout the body's water. The liver then breaks it down, primarily using the enzyme alcohol dehydrogenase, at a steady pace that is largely independent of how much you have consumed. This is the key reason there is no quick fix for being drunk: if your BAC is 0.10%, it will take roughly six to seven hours to return to zero, no matter what you do in the meantime. Each standard drink raises BAC by roughly 0.02% to 0.04% depending on your size and sex, while your body removes about 0.015% per hour.
The same number of drinks can produce very different BAC levels in different people, and even in the same person on different occasions. Major factors include:
Because of all these variables, treat any calculated BAC as a rough estimate, not a precise measurement.
A "standard drink" is a useful concept because different beverages contain very different amounts of alcohol per serving. In the United States, one standard drink contains about 14 grams of pure alcohol, which is roughly equivalent to:
These all contain a similar amount of alcohol, which is why this calculator asks for both the size and the ABV of your drinks rather than just a count. A single large cocktail or a strong craft beer can equal two or three standard drinks, so being precise about size and strength gives a far more accurate estimate.
The table below summarizes the impairment generally associated with different BAC ranges. Sensitivity varies widely between individuals, and these effects are typical rather than guaranteed.
| BAC (%) | Typical effects |
|---|---|
| 0.010 – 0.029 | Average individual appears normal. |
| 0.030 – 0.059 | Mild euphoria, relaxation, joyousness, talkativeness, decreased inhibition. |
| 0.060 – 0.099 | Blunted feelings, reduced sensitivity to pain, euphoria, disinhibition, extraversion. |
| 0.100 – 0.199 | Over-expression, boisterousness, possibility of nausea and vomiting. Impaired balance, speech, vision, and reaction time. |
| 0.200 – 0.299 | Nausea, vomiting, emotional swings, partial loss of understanding, impaired sensations, possibility of stupor. |
| 0.300 – 0.399 | Stupor, central nervous system depression, loss of understanding, lapses in and out of consciousness, low possibility of death. |
| 0.400 – 0.500 | Severe central nervous system depression, coma, possibility of death. |
| > 0.500 | High possibility of death. |
In most of the United States, it is illegal to drive with a BAC of 0.08% or higher (0.05% in Utah). For commercial drivers the limit is typically 0.04%, and for drivers under 21 most states enforce "zero tolerance" laws with limits as low as 0.00% to 0.02%. Many other countries set their general limit at 0.05%, and some at 0.02% or even zero. Penalties for driving under the influence are severe and can include fines, license suspension, and jail time — and impairment that endangers yourself and others begins well below any legal limit. Even a BAC of 0.02% measurably affects judgment and the ability to track a moving target or perform two tasks at once.
The only genuine way to lower your BAC is to wait. Your liver eliminates alcohol at a fixed rate of roughly 0.015% per hour, and nothing reliably speeds that up. Popular "remedies" are myths: coffee may make you feel more alert but does nothing to reduce alcohol in your blood — it can even make you a more dangerous "wide-awake drunk." Cold showers, exercise, greasy food, and energy drinks likewise have no effect on elimination. If you have been drinking, the safe choices are to wait it out, arrange a ride with a sober driver, use a taxi or rideshare, or stay where you are. Drinking water and eating may help you feel better and prevent some of a hangover, but they will not bring your BAC down faster.
A BAC calculator gives a reasonable estimate based on the Widmark formula, but real BAC depends on many factors it cannot capture — food intake, body composition, metabolism, medications, and individual variation. Treat the result as a ballpark figure, not a precise reading. Only a breathalyzer or blood test measures actual BAC.
Since the body eliminates roughly 0.015% of BAC per hour, you can estimate the time by dividing your current BAC by 0.015. For example, a BAC of 0.08% takes a little over five hours to clear. This calculator shows the estimated number of hours until your BAC returns to 0%.
On average, women have a higher proportion of body fat and a lower proportion of body water than men of the same weight. Because alcohol distributes through body water, the same amount of alcohol becomes more concentrated in a woman's bloodstream, producing a higher BAC. The Widmark formula accounts for this with different distribution ratios for men and women.
No. Nothing speeds up the elimination of alcohol from your blood. Coffee, cold showers, exercise, and food may change how you feel, but your BAC falls only with time as your liver does its work. Believing otherwise can lead to dangerous decisions like driving while still impaired.
Rather than assuming a fixed "drink," this calculator asks for the size and ABV of each beverage so it can compute the actual grams of alcohol. A standard U.S. drink is about 12 oz of 5% beer, 5 oz of 12% wine, or 1.5 oz of 40% spirits — each containing roughly 14 grams of alcohol. Larger or stronger servings count as more than one drink.
Not necessarily. The calculator is an estimate and your real BAC could be higher. Impairment begins well below 0.08%, and lower limits apply to commercial and underage drivers. The safest choice after drinking any alcohol is not to drive at all.
This BAC Calculator is provided for educational and informational purposes only and is not medical, legal, or safety advice. The estimated BAC may differ significantly from your actual blood alcohol content. Do not use this calculator to decide whether you are fit to drive or operate machinery. If you have consumed alcohol, do not drive. Always seek professional help for concerns about alcohol use.