BAC Calculator: The Complete Guide
Estimate your blood alcohol concentration. Enter your sex, body weight, the number of standard drinks, and how long ago you started drinking to get a rough BAC using the Widmark formula.
Who the BAC Calculator is for
Adults curious about how alcohol affects BAC — for awareness only, never to decide whether to drive.
How to use the BAC Calculator
- Type your values into the fields above — pick your currency or units where the calculator offers them.
- Results update automatically as you type; there's no submit button and nothing is sent to a server.
- Adjust any input to compare scenarios, then copy the result with a single click.
How it works
Widmark: BAC% = (alcohol grams ÷ (weight in grams × r)) × 100 − 0.015 × hours, where r is 0.68 for men and 0.55 for women, and each standard drink is about 14 g of alcohol.
Features
- Widmark estimate
- Standard-drink based
- Male & female factors
- kg or lb
An estimate only — never a green light
This calculator gives a rough Widmark estimate of blood alcohol concentration. Real BAC depends on food, hydration, medications, metabolism, and the exact drink strength, which no formula captures. Impairment can occur below any legal limit, so never use a calculator to decide whether you're safe to drive. When in doubt, don't drive.