What is BAC Calculator?
The Blood Alcohol Concentration (BAC) Calculator uses the Widmark equation to estimate percentage of alcohol in the bloodstream, subtracting metabolic elimination over elapsed time.
How to Use This Calculator
- Select sex and weight.
- Specify standard alcoholic drinks consumed.
- Enter hours since first drink.
- Review your theoretical BAC and estimated time to full sobriety.
The Mathematical Formula & Variables
BAC = [(Drinks * 14 grams) / (Weight in grams * r) * 100] - (0.015 * Hours)
Variables Definition
| Symbol / Variable | Name | Description |
|---|---|---|
14 grams |
Standard Drink | US standard drink alcohol content. |
0.015/hr |
Beta Metabolic Rate | Average liver alcohol elimination rate per hour. |
r |
Distribution Ratio | 0.68 for men, 0.55 for women. |
Step-by-Step Worked Example
Scenario: Male weighing 170 lbs (77,110 g) having 3 drinks over 2 hours.
- Alcohol consumed = 3 * 14g = 42 grams.
- Body distribution = 77,110 * 0.68 = 52,434.8 g.
- Gross alcohol concentration = (42 / 52,434.8) * 100 = 0.0801%.
- Metabolized over 2 hours = 0.015 * 2 = 0.0300%.
- Net BAC = 0.0801% - 0.0300% = 0.0501%.
Result: BAC = ~0.05% (Under 0.08% Legal Limit)
Frequently Asked Questions
Can coffee, cold showers, or food speed up sobriety?
No. Only time allows the liver enzyme alcohol dehydrogenase to metabolize alcohol. Coffee and water do not accelerate the biological 0.015%/hr elimination rate.