Blood Alcohol Calculator (BAC)
Estimate BAC from drinks, weight, and time using Widmark.
Estimated BAC
0.055%
Impaired
Estimate only. Real BAC depends on what you drank, when, food in your stomach, medications, and individual physiology. Never use this to decide whether to drive. If you drank, do not drive.
Uses the Widmark formula with r = 0.68 (male) and 0.55 (female), and assumes a US standard drink contains 14 g of pure alcohol. Alcohol is metabolized at roughly 0.015% BAC per hour.
About
Rough estimate of blood alcohol concentration based on the Widmark formula. Real BAC depends on what you drank, when, food in your stomach, medications, and individual physiology. Never use this to decide whether to drive.
How to use
- Enter your sex and weight.
- Enter how many standard drinks you've had.
- Enter how many hours since the first drink.
- Read the estimated BAC and status.
FAQ
Can I trust this enough to drive?+
No. This is an estimate with a wide error range. The only safe number behind the wheel is zero. If you drank, do not drive.
What's a 'standard drink'?+
14 g of pure alcohol (US definition). That's roughly a 12 oz beer at 5%, a 5 oz glass of wine at 12%, or a 1.5 oz shot of 80-proof spirits.