Online Calculator

BAC Calculator

Educational Widmark model: drinks, body weight, sex, and elapsed time → estimated BAC. Estimates vary person to person.

Estimated BAC

0.040%

Hours until ~0.00%
2.7
vs 0.08% legal limit
Below limit
This is an educational estimate only — NEVER drive after drinking regardless of the number shown.

How the BAC Calculator works

The calculation follows the standard method used across the US — no shortcuts, no hidden assumptions. Here is exactly what happens behind the scenes:

Formula

BAC ≈ A×5.14/(W×r) − 0.015×hours

Frequently Asked Questions

Is this legal advice about driving?

Absolutely not. Impairment begins well below legal limits, individual metabolism varies widely, and only a breathalyzer/blood test measures actual BAC. Never drive after drinking.

What is a 'standard drink'?

US: 14 g alcohol — 12 oz beer (5%), 5 oz wine (12%), or 1.5 oz spirits (40%). Craft IPAs and heavy pours routinely exceed these.