Blood Alcohol Calculator
Estimate blood alcohol concentration from weight, sex, standard drinks and time — for education only.
How to use it
- Enter your details Sex and body weight.
- Add drinks and time Standard drinks and hours since the first.
- Read the estimate An approximate blood alcohol percentage.
Examples
| 2 drinks, 80 kg M | ~0.05% then falls |
|---|---|
| per hour | −0.015% |
About this tool
This calculator estimates blood alcohol concentration from your weight, sex, the number of standard drinks and the time since your first drink, using the well-known Widmark formula and a typical rate of metabolism.
It is strictly an educational estimate. Real blood alcohol depends on many factors this can’t capture — food, medication, body composition and individual differences — so the number can be very wrong for any given person. Never use it to decide whether it is safe or legal to drive. Everything is computed in your browser.
Frequently asked questions
How is BAC estimated?
It uses the Widmark formula with sex-based body-water factors, then subtracts roughly 0.015% per hour for metabolism. It's an approximation.
Can I use this to decide whether to drive?
No. Real BAC depends on food, medication, health and more. Never use any estimate to decide whether it's safe or legal to drive.
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Updated June 14, 2026