Estimated BAC
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Rough estimate only (Widmark formula) — actual BAC varies by individual and can be meaningfully different from this number. Never use this to decide whether it's safe to drive. When in doubt, don't drive — call a cab, rideshare, or a sober friend.
Free BAC Calculator
Estimate blood alcohol content using the Widmark formula.
The Widmark formula is a population-average estimate — actual BAC varies with food intake, metabolism, medication, and individual physiology, and can be meaningfully off for any given person. This tool is for general information only. It is not a substitute for a breathalyzer or blood test, and should never be used to decide whether it's safe to drive — when in doubt, don't drive.
Frequently Asked Questions
Is this accurate enough to decide if I can drive?
No. This is a rough population-average estimate, not a substitute for a breathalyzer, and individual factors can shift actual BAC significantly. Never use it to make a driving decision.
What counts as one standard drink?
In the US, a standard drink is about 14g of pure alcohol — roughly a 12oz beer, a 5oz glass of wine, or 1.5oz of spirits.