BAC Calculator

The BAC Calculator is a free online tool that estimate blood alcohol content using the widmark formula with drink presets, custom inputs, eating modifier, and metabolization timeline.. It runs entirely in your browser with no installation or sign-up needed.

BAC = (alcohol grams / (body weight grams x body water constant)) - (0.015 x hours). Body water: male 0.68, female 0.55.

Estimate only. Actual BAC varies by metabolism, food, medications, tolerance. Never rely on any calculator to determine if safe to drive.

Beer (12oz/5%), Wine (5oz/12%), Shot (1.5oz/40%), Cocktail (6oz/15%), plus custom volume + ABV input and standard drink counting.

Yes, the BAC Calculator is 100% free with no registration, no hidden fees, and no usage limits. All processing happens locally in your browser, ensuring complete privacy.

Absolutely. The BAC Calculator processes everything client-side in your browser. No data is uploaded to or stored on any server. Your content remains private on your device at all times.

Yes, the BAC Calculator is fully responsive and works on smartphones and tablets. You can use it on any device with a modern web browser -- no app download required.

No account or registration is needed. Simply open the BAC Calculator in your browser and start using it immediately. There are no sign-up walls or usage restrictions.

Simply enter your input in the provided field, adjust any settings to your preference, and the tool will process it instantly. You can then copy the result to your clipboard or download it.

The BAC Calculator works in all modern browsers including Chrome, Firefox, Safari, Edge, and Opera. For the best experience, use the latest version of your preferred browser.

Your liver eliminates alcohol at a roughly fixed rate of about 0.015 BAC percentage points per hour, and that pace barely changes no matter what you do. So if your estimated BAC peaks at 0.08%, it takes roughly five to six hours to return to 0.00%, while a peak of 0.15% needs closer to ten hours. Only time lowers your BAC; coffee, water, a cold shower, or sleep do not speed up metabolism. This calculator does the math for you: after you enter your drinks, weight, sex, and hours elapsed, it shows the estimated time until your BAC reaches zero, the time until it drops below 0.08%, and an hour-by-hour timeline of the decline. Remember it is an estimate only, so build in a generous margin before assuming you are clear.

The Widmark formula spreads alcohol through your body water, and men and women carry different proportions of it. The tool uses a body-water constant of 0.68 for males and 0.55 for females, reflecting that women, on average, have a higher fat-to-water ratio, so the same amount of alcohol is diluted in less water and produces a higher concentration. That is why two people of identical weight drinking the same number of beers can land at noticeably different BAC levels. Body weight matters too, since more total water lowers the concentration further. These are population averages, not personal measurements, so individual hydration, hormones, and body composition shift real results. Pick your sex and enter your weight in this calculator to see how those factors change the estimate for your specific drinks.

A standard drink is a fixed amount of pure alcohol, not a fixed glass size, which is why a single cocktail can equal two or three standard drinks. In the United States one standard drink contains 14 grams of alcohol, while the Australian and UK definition uses 10 grams; this calculator lets you choose either. As a rough guide, one US standard drink is about a 12-ounce beer at 5% ABV, a 5-ounce glass of wine at 12%, or a 1.5-ounce shot of 40% spirits. Higher-ABV craft beers, generous wine pours, and mixed drinks routinely exceed one standard drink, which is how people underestimate their intake. Use the standard-drinks mode to enter a count directly, or the preset and custom-drink options to break down exactly what you had and see the total in grams.

Eating does not change how much alcohol you ultimately absorb, but it slows how fast it hits your bloodstream. Food, especially a meal with protein and fat, delays stomach emptying so alcohol reaches your small intestine more gradually, which lowers and flattens your peak BAC compared with drinking on an empty stomach. This calculator models that with an eating modifier that reduces estimated absorption by about 20% when you toggle it on, reflecting a full stomach. It is important to understand the limit: food blunts the peak, but your liver still eliminates alcohol at the same fixed rate, so eating does not help you sober up faster once the alcohol is in your system. Switch the eating modifier on or off to compare how a full versus empty stomach shifts your estimated BAC for the same drinks.

In most US jurisdictions the legal limit for driving is a BAC of 0.08%, and reaching it generally means measurable impairment to coordination, reasoning, and reaction time. This calculator labels results against common thresholds: 0.00 to 0.05% is shown as legal with little measurable impairment, 0.05 to 0.08% as impaired with reduced judgment and alertness, 0.08% and above as over the limit, 0.15% and up as dangerous with major motor impairment, and 0.30% and up as life-threatening. Many places set lower limits for commercial, novice, or zero-tolerance drivers, so 0.08% is not universal. Most importantly, these are estimates from a formula, not a breathalyzer reading, and impairment can begin below any legal cutoff. Never use this tool to decide whether you are safe to drive; enter your details to understand the science, not to justify getting behind the wheel.