BAC Calculator

Estimate Blood Alcohol Content (BAC) based on drinks consumed, time, weight, and gender.

Disclaimer: This calculator provides estimates only. Never drink and drive. Blood alcohol levels vary significantly by individual. Do not use this to determine if you are safe to drive.

Estimated BAC

0.048

Light feeling, relaxed, slight warmth

Total alcohol consumed42.0g
Peak BAC (before elimination)0.078
Est. hours until sober5.2 hrs

BAC Reference

0.02Light feeling, relaxed, slight warmth
0.05Lowered inhibitions, mild impairment of judgment
0.08Legal driving limit in the US, clear impairment
0.10Significant impairment of coordination and reaction time
0.15Major impairment, possible nausea, loss of balance
0.20Confusion, stupor, possible blackout
0.30Possible unconsciousness, dangerous
0.40Potentially fatal

How to Use the BAC Calculator

  1. Select your biological sex. Sex affects the Widmark r factor (0.68 for men, 0.55 for women), which accounts for the proportion of body water. Women have less body water per pound of body weight, so the same alcohol produces a higher BAC.
  2. Enter your weight. Heavier individuals have more body water to dilute alcohol, resulting in lower BAC for the same drinks. Enter in pounds or kilograms.
  3. Select drink type and quantity. A standard drink is defined as 14 grams of pure alcohol: 12 oz regular beer (5% ABV), 5 oz wine (12% ABV), or 1.5 oz spirits (40% ABV). Use Custom to enter any drink size and ABV percentage.
  4. Enter hours since your first drink. The calculator subtracts elimination (0.015% BAC per hour) from total absorbed alcohol to estimate your current BAC.

This calculator provides estimates only. Individual variation is significant. Never use this to determine whether it is safe to drive.

Widmark BAC Formula and Effects

BAC = (A / (W × r)) × 100 - (0.015 × H)

A = alcohol in grams consumed
W = body weight in grams
r = 0.68 (men) or 0.55 (women)
H = hours since first drink

Alcohol grams = oz × 29.57 × (ABV%) × 0.789

BAC effects at different levels:

BAC %Typical EffectsLegal Status
0.01-0.03Mild relaxation, slight warmthLegal everywhere
0.04-0.06Lowered inhibitions, mild impairmentLegal (impaired)
0.07-0.09Impaired balance, reaction time reducedDUI in most US states
0.10-0.15Slurred speech, poor coordinationIllegal everywhere
0.16-0.30Confusion, memory blackout possibleIllegal
0.30+Possible unconsciousness, life riskMedical emergency

Frequently Asked Questions

On average, the liver metabolizes about 0.015% BAC per hour, equivalent to roughly one standard drink per hour for most people. This rate is primarily determined by liver enzyme activity and is relatively constant regardless of actions taken. Coffee, water, exercise, and food consumed after drinking do not speed up metabolism. Only time reduces BAC after drinking.

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