Blood Alcohol Calculator
Estimate your blood alcohol concentration (BAC) from drinks, body weight, sex and time using the Widmark formula — free online estimator. — free, fast and private.
How to use Blood Alcohol Calculator
- Enter how many standard drinks you had (one standard drink is about 14 g of pure alcohol).
- Enter your body weight and sex, and the hours since your first drink.
- Click Estimate BAC to see your estimated blood alcohol level.
Note: this tool runs in your browser. Nothing is uploaded.
Disclaimer: this is an estimator only — please see a qualified professional for advice about your specific situation. This estimate is not medical or legal advice and cannot tell you whether it is safe or legal to drive. Never drink and drive — if you have been drinking, do not drive. If you are concerned about alcohol use, speak to a doctor.
Frequently Asked Questions
How accurate is this BAC estimate?
It uses the Widmark formula, a standard estimation method, but it is only an approximation. Real BAC depends on food, health, medication and metabolism, so the true value can differ. Never use it to decide whether you are safe to drive.
Is this tool free to use?
Yes, it is 100% free with no sign-up. Your data stays in your browser.
Is my data uploaded or stored?
No. This tool runs entirely in your browser — nothing you enter is uploaded to a server.
Can I use it on my phone?
Yes, it is fully mobile-friendly and works in any modern browser on phone, tablet or computer.