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BAC Calculator

Estimate blood alcohol content using the Widmark formula.

Rough estimate only — many factors affect true BAC. Never drive after drinking, regardless of this estimate. If you or someone else needs help, call 911 (US) or your local emergency number.

This estimates blood alcohol content using the Widmark formula, a well-established method that accounts for body weight, sex, and drinks consumed over time — for educational awareness, not for deciding whether it's safe to drive.

Why this is only a rough estimate

True BAC is affected by many factors this formula can't fully capture — food consumed, metabolism, medication, and individual variation all shift actual BAC away from a formula-based estimate. Never use an estimate like this to decide whether you're safe to drive.

Frequently asked questions

What BAC level is legally impaired?

Legal limits vary by country and sometimes by state or region (commonly 0.05% to 0.08%) — but any amount of alcohol can impair driving ability regardless of the legal threshold.

How long does it take for BAC to return to zero?

The body metabolizes alcohol at a roughly steady rate over time, but this varies by individual — the only reliable way to be at zero is to wait it out, since nothing meaningfully speeds up alcohol metabolism.