Blood Alcohol Content (BAC) Calculator

Enter your weight, sex, and number of drinks to estimate your blood alcohol content using the Widmark formula.

⚠️ Please read before using: This calculator provides only a rough, statistical estimate for general-knowledge purposes. It must never be used as evidence of your actual blood alcohol content or to decide whether you are fit to drive. Never drive after drinking, regardless of what this calculator shows.

How is this calculated?

This calculator uses the Widmark formula, devised in the 1930s by Swedish scientist Erik Widmark. It divides the amount of alcohol consumed by your body weight and a distribution ratio (which differs by sex), then subtracts the alcohol metabolized over time (roughly 0.015% per hour).

Why is this only a reference estimate?

Actual blood alcohol content depends on many individual factors β€” body fat percentage, liver function, whether you've eaten, how fast you drank, and more β€” so this formula only gives an average-case estimate that can differ significantly from your real level. Legal limits for driving also vary by country and region, so no matter what this calculator shows, the safest choice is to never drive after drinking.

Frequently Asked Questions

Can I use this result to decide if I'm safe to drive?

Absolutely not. This calculator is educational content that shows a statistical estimate only. Any real determination must be made with far more accurate breath or blood tests. Never drive after drinking, no matter what this tool shows.

What counts as a "standard drink" here?

This calculator uses roughly 14 grams of pure alcohol as one standard drink β€” the average amount of alcohol in a typical beer (about 350ml at 5% ABV) or a glass of wine (about 150ml at 12% ABV).