"How Drunk Am I?" Calculator 🍺
BAC estimated. Decisions still yours. Call a ride.
1 standard drink ≈ 355ml beer, 150ml wine, or 45ml spirits
This is an estimate, not a fact.
Blood alcohol content depends on far more than what this calculator can measure — medication, food, sleep, health conditions, and body chemistry all change the real number. Never use this tool to decide whether it's safe to drive.
If there's any doubt, don't drive. Call a taxi, use a rideshare app, ask a sober friend, or stay where you are. It's always cheaper than the alternative.
About This Calculator
How It Works
This calculator uses the Widmark formula — the same equation used in forensic science and law enforcement — to estimate blood alcohol content based on weight, biological sex, number of standard drinks consumed, and time elapsed since the first drink. Your body metabolizes roughly 0.015% BAC per hour, which the formula subtracts from the raw alcohol load. The result is a percentage that corresponds to how much alcohol is estimated to be in your bloodstream at that moment.
The Formula
BAC (%) = (drinks × 14) / (weight_kg × r × 10) − (0.015 × hours). r = 0.68 for men, 0.55 for women. Result expressed as a percentage.
When to Use This
This is most useful for building intuition about how alcohol affects you specifically — how body weight changes the numbers, how time helps, how quickly a few drinks accumulate. It's not a tool for deciding whether to drive. It's a harm-reduction tool: understanding the rough math helps people make better decisions before they're impaired. If you're using it to decide if you're 'okay to drive,' the answer is call a ride.
Limitations
The Widmark formula is a population-level model, and individual BAC can vary by up to 50% based on genetics, food intake, hydration, medications, sleep deprivation, and tolerance. It also assumes standard drink sizes — a heavy pour or high-ABV craft beer changes the math significantly. This calculator should never be used to make safety decisions. A breathalyzer is more accurate; a cab is safer.
Example
A 70kg man who drinks 3 standard drinks in 2 hours has an estimated BAC of ~0.05%. But eat a meal first and it might be ~0.03%. Food matters.
Did You Know?
The Widmark formula was developed in the 1930s by Swedish physician Erik Widmark. It's still the gold standard for forensic BAC estimation. Your actual BAC can vary by up to 50% based on genetics, medications, and food intake.