BAC Calculator
Estimate blood alcohol content based on drinks consumed, body weight, and time elapsed. This is an educational estimate only — never use it to decide whether it's safe to drive.
This is an estimate — not a safety determination
This calculator uses a standard estimation formula (a version of the Widmark equation) to give a rough idea of blood alcohol content. It is intended for educational awareness only. It cannot account for individual metabolism, medication interactions, food intake, drink strength variation, or many other real factors that affect actual BAC — meaning your true BAC could be meaningfully different from this estimate, in either direction.
No BAC level is 'safe' for driving, and impairment to reaction time and judgment begins well below most legal limits. This tool should never be used to decide whether you or someone else is fit to drive. If you've been drinking, arrange a rideshare, taxi, designated sober driver, or public transit instead.
What counts as a 'standard drink'
A standard US drink is typically defined as about 14 grams (0.6 oz) of pure alcohol — roughly a 12 oz regular beer, a 5 oz glass of wine, or a 1.5 oz shot of 80-proof spirits. Stronger beers, larger pours, and mixed drinks with multiple shots can contain significantly more alcohol than one standard drink, which this calculator can't detect from a simple drink count.
If you're tracking consumption for awareness, it's worth being honest about actual pour sizes and drink strength rather than assuming every drink equals exactly one standard unit.
Frequently asked questions
Can I use this to decide if I'm safe to drive?
No. This is an educational estimate only, and actual impairment can occur below what any calculator predicts. Never use a BAC estimate to make a driving decision — always arrange alternative transportation after drinking.
Why might my actual BAC differ from this estimate?
Real BAC depends on many factors this simple formula can't capture, including individual metabolism, food consumed, medications, drink strength, and rate of consumption — treat this as a rough educational estimate, not a precise measurement.