Blood Alcohol (BAC) Calculator

A rough blood alcohol estimate from drinks, weight, and time.

Quick answer: Free BAC Calculator online. Get a rough Blood Alcohol Concentration estimate based on your drinks, body weight, and time passed.

h
Estimated BAC0.058%
StatusImpaired — do not drive
WarningA rough estimate only. Never use this to decide whether to drive — never drink and drive.

computed locally — nothing leaves your browser

Estimate blood alcohol concentration from the number of standard drinks, your weight and sex, and time elapsed using the Widmark formula.

How it works

  1. Enter your physiological data (weight, sex).
  2. Enter the number of standard drinks you consumed and hours elapsed.
  3. The calculator uses the Widmark formula to provide a BAC estimate.

Frequently asked questions

Can I use this to decide if I can drive?

Absolutely not. This is a rough estimate that ignores food, medication, and individual metabolism. Never drink and drive, period.

What is a standard drink?

In the US, about 14 grams of pure alcohol: a 12 oz beer, 5 oz wine, or 1.5 oz spirits.

Why is my real BAC different?

Food, hydration, medications, health, and genetics all shift actual BAC well beyond what any formula predicts.

More in Health & Fitness