Drinks, BAC & Calories
Last reviewed: May 2026
Alcohol (ethanol) is absorbed through the stomach and small intestine, enters the bloodstream, and is processed primarily by the liver at roughly one standard drink per hour.[1] Blood Alcohol Concentration (BAC) depends on your weight, sex, rate of consumption, food intake, and individual metabolism. Drinking on an empty stomach can produce peak BAC 2-3 times faster than drinking with a meal. Use the BAC Time Calculator to estimate your blood alcohol level over time.
| Beverage | Serving Size | ABV | Standard Drinks | Calories |
|---|---|---|---|---|
| Regular beer | 12 oz | 5% | 1.0 | 150 |
| Craft IPA | 16 oz (pint) | 7% | 1.9 | 280 |
| Wine (red) | 5 oz | 13% | 1.1 | 125 |
| Spirits (vodka, whiskey) | 1.5 oz | 40% | 1.0 | 97 |
| Margarita | 8 oz | ~13% | 1.7 | 275 |
| Hard seltzer | 12 oz | 5% | 1.0 | 100 |
Blood Alcohol Content (BAC) measures the concentration of alcohol in the bloodstream, expressed as a percentage by weight. A BAC of 0.08% — the legal driving limit in all U.S. states — means 0.08 grams of alcohol per 100 milliliters of blood. BAC is determined by the balance between alcohol absorption (from the gastrointestinal tract into the bloodstream) and alcohol elimination (primarily through liver metabolism). The body metabolizes alcohol at a roughly constant rate of approximately 0.015-0.017% BAC per hour, equivalent to approximately one standard drink per hour for most adults. This rate is largely fixed and cannot be accelerated by coffee, cold showers, exercise, or any folk remedy — only time reduces BAC.
The Widmark formula provides a widely used estimate of BAC: BAC = (Alcohol consumed in grams / (Body weight in grams × Widmark factor)) - (Elimination rate × Hours since drinking). The Widmark factor (also called the volume of distribution) averages 0.68 for men and 0.55 for women, reflecting differences in body water content and body composition. Women generally reach higher BAC levels than men of the same weight after consuming the same amount of alcohol because women typically have lower body water percentages and higher body fat percentages, and alcohol is water-soluble.
A "standard drink" in the United States contains approximately 14 grams (0.6 fluid ounces) of pure alcohol. This corresponds to 12 ounces of regular beer (5% ABV), 5 ounces of wine (12% ABV), or 1.5 ounces of distilled spirits (40% ABV/80 proof). However, many beverages exceed standard drink sizes: craft beers often range from 6-12% ABV, making a 12-ounce pour equivalent to 1.2-2.4 standard drinks. A typical restaurant wine pour is 6-8 ounces rather than 5, and many cocktails contain 2-3 shots of spirits. Without awareness of these discrepancies, people commonly underestimate their consumption by 30-50%.
International standard drink definitions vary significantly. The Australian standard drink contains 10 grams of alcohol, the UK unit contains 8 grams, and the Japanese standard drink contains 19.75 grams. These differences make international comparisons of drinking guidelines confusing — the UK guideline of "no more than 14 units per week" translates to approximately 8 U.S. standard drinks, which sounds more restrictive but is actually comparable in total alcohol to the U.S. guideline of no more than 14 standard drinks per week for men. Understanding what constitutes a standard drink in your country's framework is essential for accurately assessing consumption patterns against health guidelines.
Several factors beyond body weight and biological sex affect how quickly alcohol is absorbed and how high BAC rises. Food consumption is the most significant modifier — eating before or while drinking slows gastric emptying and reduces peak BAC by 20-40% compared to drinking on an empty stomach. Fatty foods are particularly effective at slowing absorption because they delay gastric emptying more than proteins or carbohydrates. Carbonation accelerates absorption — champagne and cocktails mixed with carbonated beverages may produce faster-rising BAC than the same amount of alcohol in non-carbonated form.
Drinking speed directly affects peak BAC — consuming four drinks in one hour produces a much higher peak BAC than the same four drinks spread over four hours, because absorption outpaces elimination during rapid consumption. Medications can interact dangerously with alcohol — many prescription and over-the-counter drugs (including antihistamines, antidepressants, pain relievers, and anti-anxiety medications) amplify alcohol's sedative effects without necessarily increasing BAC, creating impairment greater than BAC alone would predict. Genetic variations in alcohol-metabolizing enzymes (alcohol dehydrogenase and aldehyde dehydrogenase) affect metabolism rates — some individuals of East Asian descent carry genetic variants that slow aldehyde metabolism, producing the "Asian flush" response and different BAC kinetics.
Current medical evidence provides a clear picture of alcohol's health effects at different consumption levels. The 2020-2025 Dietary Guidelines for Americans recommend that adults who choose to drink limit consumption to 2 drinks or fewer per day for men and 1 drink or fewer per day for women. Heavy drinking is defined as more than 4 drinks on any day or 14+ per week for men, and more than 3 drinks on any day or 7+ per week for women. Binge drinking is defined as consuming 5+ drinks (men) or 4+ drinks (women) within approximately 2 hours.
Earlier research suggesting cardiovascular benefits of moderate drinking has been substantially revised. Large-scale Mendelian randomization studies and improved meta-analyses controlling for the "sick quitter" bias have found that the safest level of alcohol consumption for overall health is zero or near-zero drinks per week. Alcohol is a confirmed carcinogen linked to cancers of the breast, liver, mouth, throat, esophagus, and colon, with risk increasing linearly with consumption — even moderate drinking increases breast cancer risk by approximately 5-10% per drink per day. Liver disease, pancreatitis, cardiovascular damage, immune suppression, and neurological effects add to the health burden at higher consumption levels. For related health tracking, see our Sobriety Calculator and Calorie Deficit Calculator.
The legal BAC limit for driving is 0.08% in all U.S. states, most Canadian provinces, and the UK (Scotland uses 0.05%). Many European countries set the limit at 0.05%, while others (Czech Republic, Hungary, Romania) enforce a zero-tolerance 0.00% limit. For commercial drivers in the U.S., the limit is 0.04%, and for drivers under 21, most states enforce zero tolerance (0.00-0.02%). Impairment begins well below the legal limit — studies show measurable declines in reaction time, divided attention, and judgment at BAC levels as low as 0.02%, and significant impairment is typical by 0.05%. The legal limit represents a regulatory threshold, not a safety threshold — drivers with BAC between 0.05% and 0.08% have approximately 2-3 times the crash risk of sober drivers, even though they are technically under the legal limit.
→ One standard drink = 14g pure alcohol. Use this to convert any beverage.[1]
→ Eating slows absorption. A full meal before drinking can reduce peak BAC by 20-30%.[2]
→ Track calories from drinks. Alcohol calories add up fast and are easy to forget when dieting.
→ Know the legal BAC limit. 0.08% in all U.S. states; impairment begins at 0.02-0.03%.
See also: BAC Calculator · Calorie Calculator · Water Intake · Blood Pressure