BAC Calculator - Blood Alcohol Content Estimate

It depends on body weight, sex, food intake, and how fast you drink — there's no single number. As a rough guide, a 70 kg man may reach 0.08% after about 4 standard drinks in an hour. A 55 kg woman might hit 0.08% with 2 to 3 drinks in the same time. A standard drink contains about 14 grams of alcohol — one 330 ml beer at 5%, 150 ml of wine, or 45 ml of spirits. Clinicians often advise patients in casualty: never use these numbers to decide whether to drive — individual response varies more than you think.

Your liver clears alcohol at roughly 0.015% BAC per hour — that's about one standard drink per hour for most adults. So a peak BAC of 0.08% takes around 5 to 6 hours to fully clear. Alcohol can be detected in breath for 12 to 24 hours, urine for up to 48 hours, hair follicle tests for up to 90 days. Liver enzymes, body weight, hydration, and how recently you ate all affect the rate. Coffee, cold showers, and exercise don't speed it up — only time does.

No. A BAC calculator gives an estimate based on average liver clearance, but real BAC depends on factors no calculator can measure — your liver enzyme levels that day, what you ate, medications, fatigue, even genetics. I've seen breath test readings differ from calculator predictions by 30% or more. The legal limit in India is 0.03%, far below the level where you 'feel' drunk. The honest medical advice: if you've been drinking, don't drive at all. Use a cab, a friend, or wait until the next morning.

Alcohol distributes itself in the water content of your body, not in fat. Lighter people have less total body water, so the same drink reaches a higher concentration in their blood. Women generally have less body water per kg than men — that's why an identical drink hits them harder. Muscle holds more water than fat, so two people of the same weight can have different BACs depending on body composition. The Widmark formula uses a distribution factor — about 0.68 for men and 0.55 for women — to capture this difference.

The Widmark formula is the standard: BAC = (alcohol in grams ÷ (body weight in grams × distribution ratio)) × 100, then subtract roughly 0.015% for every hour since you started drinking. The distribution ratio is around 0.68 for men, 0.55 for women. Example: 70 kg man, three standard drinks (42 g alcohol), 2 hours in — gives roughly (42 ÷ 47600) × 100 − 0.03 ≈ 0.058%. It's an estimate, not a measurement. Real breathalyzers measure the actual breath alcohol, which is far more reliable than any formula.

Time. That's the only real answer. Your liver oxidises alcohol at a near-constant rate of about 0.015% per hour and nothing reliably changes that. Coffee makes you alert but still drunk. Cold showers wake you up but don't lower BAC. Greasy food before drinking slows absorption, so peak BAC is lower — but eating after drinking doesn't help much. Hydration prevents the morning hangover but doesn't sober you up. In casualty we manage severe intoxication with IV fluids, glucose, and observation, but even there, time does most of the work.