BAC Calculator

Estimate blood alcohol concentration from drinks consumed, body weight, and time elapsed.

About this calculator

The Widmark formula estimates BAC from alcohol consumed (one U.S. standard drink ≈ 14 g of pure alcohol), body water distribution, and elimination at about 0.015% per hour. All 50 states set the driving limit at 0.08% for adults 21+.

Formula

BAC% = (drinks × 14 g ÷ (weight g × r)) × 100 − 0.015 × hours r = 0.68 (men) / 0.55 (women)

Results are estimates for information only — not medical advice. Sources: WHO, CDC, and peer-reviewed research.