BAC Calculator
Estimate blood alcohol content using a Widmark-style formula from drinks consumed, body weight, time elapsed, and sex. Planning only—not legal or medical advice.
FAQ for this calculator
- Is 0.08% the legal limit?
- Many U.S. states use 0.08% for drivers 21+—limits vary by jurisdiction and age.
- Accurate for breath tests?
- No—this is a simplified estimate; devices and labs measure differently.
- Food and hydration?
- Not modeled—eating slows absorption but does not eliminate impairment.
- Can I use this in court?
- No—never rely on this calculator for legal decisions.
How to use the BAC estimate calculator
Widmark estimates peak BAC from alcohol grams divided by body water, minus hourly metabolism.
- Count standard drinks consumed.
- Enter weight and hours since the last drink.
- Select sex for the distribution ratio.
When to use this calculator
- Understanding why weight and time change BAC.
- Planning sober ride home after social drinking.
- Comparing beer vs mixed-drink counts using standard drink units.
Examples & walkthrough
- 2 drinks, 170 lb male, 2 hours → BAC below 0.08 in this model but still impaired.
- More hours elapsed lowers estimated BAC.