BAC & Alcohol Metabolism Calculator
Estimates only — never drive based on a calculator result
How Alcohol Is Metabolised — The Science
Unlike most nutrients, alcohol cannot be stored — the body treats it as a toxin and prioritises its elimination above all other metabolic processes. Approximately 90–95% of alcohol is metabolised in the liver by the enzyme alcohol dehydrogenase (ADH) at a relatively constant rate of about 0.015% BAC per hour — equivalent to roughly one standard drink per hour for an average adult. The remaining 5–10% is excreted through breath, urine, and sweat.
The Hidden Calories in Alcohol
Alcohol provides 7 kcal per gram — more than protein or carbohydrates (4 kcal/g each) and approaching fat (9 kcal/g). A pint of regular beer contains approximately 180–220 kcal. A large glass of wine (250ml, 13% ABV) contains around 190 kcal. A double spirit with a sugary mixer can reach 200–300 kcal. These calories are completely devoid of nutritional value and cannot be stored as glycogen — they are burned immediately as fuel, displacing fat oxidation. This is why alcohol causes fat gain even without contributing directly to fat storage.
Alcohol and Sleep Quality
Alcohol is a sedative that helps people fall asleep faster — but it severely degrades sleep quality in the second half of the night. As alcohol is metabolised during sleep (typically reaching low BAC levels 3–5 hours after drinking), it causes a rebound in REM-suppressing effects, resulting in fragmented sleep, more waking, and significantly reduced slow-wave (deep) sleep. Even two drinks can measurably reduce sleep quality as measured by polysomnography. Athletes who track HRV (heart rate variability) consistently report 10–40% reductions on nights following moderate alcohol consumption.
Yes, significantly. Food in the stomach — particularly protein and fat — slows gastric emptying and reduces the rate at which alcohol enters the small intestine where absorption is fastest. A full meal before drinking can reduce peak BAC by 30–50% compared to drinking on an empty stomach. This doesn't change the total amount of alcohol your body processes — it just slows down when you reach peak intoxication. It does not meaningfully change the time until you are fully sober.
No. None of these interventions affect the rate of alcohol metabolism. Coffee can make a drunk person feel more alert (caffeine counteracts some sedation) but does not lower BAC or improve driving ability — which is why "alert but impaired" can be more dangerous. The only thing that clears alcohol from the blood is time and liver metabolism. Average metabolism: 0.015% BAC per hour, regardless of what you do.