This blood alcohol content calculator estimates your BAC from the alcohol consumed, body weight, sex, and time, using the Widmark formula. Enter the values above.
Formula (Widmark)
BAC% = ( alcohol(g) ÷ (weight(g) × r) ) × 100 − 0.015 × hours
- r — distribution ratio (~0.68 men, ~0.55 women)
Example
28 g alcohol (~2 drinks), 80 kg man, 1 hour: BAC ≈ 0.036%.
This is a rough estimate only. Never use it to decide whether to drive — impairment varies and legal limits differ. If you drink, do not drive.
Important
This tool is for general educational purposes only and is not medical advice, diagnosis, or treatment. It does not replace evaluation by a qualified healthcare professional — consult one for any health decision. Last updated: August 2026.
Frequently Asked Questions
How is blood alcohol content calculated?
The Widmark formula uses grams of alcohol, body weight, a sex factor, and time. It is only an estimate.
Can I use this to decide if I can drive?
No. Never rely on an estimate to drive. Many factors affect impairment and BAC; if you have been drinking, do not drive.
How fast does BAC drop?
Roughly 0.015% per hour on average, but this varies from person to person.