Blood Alcohol Content (BAC) Estimator
A rough estimate of blood alcohol content. Do not use it to decide whether you can drive.
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Your results
Blood Alcohol Content (BAC) Estimator by TheCalcTools
How the Blood Alcohol Content (BAC) Estimator works
Enter your sex, weight, the number of standard drinks and the hours since you started.
The Widmark formula divides the alcohol consumed by body weight times a distribution ratio.
The body eliminates about 0.015% BAC per hour.
The formula
Worked example
Using the default values shown in the calculator:
| Sex | Male |
|---|---|
| Body weight (kg) | 80 |
| Standard drinks (14 g alcohol each) | 4 |
| Hours since first drink | 2 |
- Alcohol = 4 × 14 = 56 g.
- Peak-style estimate = 56 ÷ (80,000 × 0.68) × 100 = 0.103%, minus 0.03% for 2 hours = 0.073%.
- That would take about 4.9 hours to clear. This is an estimate only.
Result:
| Estimated BAC (%) | 0.073 |
|---|---|
| Hours until BAC reaches 0 | 4.9 |
| Alcohol consumed (g) | 56 |
Frequently asked questions
Can I use this to check if I can drive?
No. Actual BAC depends on food, drink strength, metabolism, medication and more, and impairment begins at low levels. If you have been drinking, do not drive.
What is a standard drink?
In the US it is 14 g of pure alcohol, about 355 ml of 5% beer, 148 ml of 12% wine or 44 ml of 40% spirits. Other countries use different sizes.
Sources and further reading
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This calculator gives general estimates for information and education. It is not medical advice and does not diagnose anything. Talk to a qualified health professional about your own situation. See our disclaimer.