Estimate your blood alcohol level with the Widmark formula from your sex, weight, number of drinks and time, and how long until it falls back to zero. Enter your values; the result updates as you type, with the method shown below.
About this calculator
This calculator estimates your blood alcohol concentration with the Widmark formula, from the alcohol you drank, your weight and sex, and the time since you started drinking. It also estimates when you will be back under common legal limits.
Enter your drinks, your weight, your sex and the time elapsed. The calculator shows the estimated level now, the likely peak and how long until it falls below 0.5 g/L, 0.2 g/L and zero.
When to use it
- Understanding how long alcohol stays in the body.
- Planning not to drive after a party.
- Learning how body weight and food change the effect.
- Prevention and education.
How to read the result
The body removes roughly 0.10 to 0.15 g/L per hour, whatever you do: coffee, water or a shower do not speed it up.
This is an estimate only. Food, health, medication and fatigue change the real level. The only safe choice is not to drive after drinking.
Mistakes to avoid
- Using the result to decide whether you can drive.
- Underestimating the size or strength of drinks.
- Thinking that sleep or coffee removes alcohol faster.
Formula
BAC (g/L) = alcohol (g) / (0.7 men or 0.6 women × weight) − 0.10 × hours
Worked example
A 75 kg man after 3 standard drinks: peak about 0.57 g/L, back to zero after about 6 hours.
Frequently asked questions
How accurate is it?
It is a rough estimate: food, health and metabolism change the real level.
How fast is alcohol removed?
About 0.10 to 0.15 g/L per hour; coffee or a shower do not speed it up.
Can I use it to decide if I can drive?
No. If you have been drinking, do not drive.
What is the limit for driving?
It depends on the country; in France it is 0.5 g/L, or 0.2 g/L for new drivers. Some countries have zero tolerance.
Does food change the result?
It slows absorption and lowers the peak, but alcohol is still eliminated at the same pace.
Can this tool tell me I can drive?
No. If you have been drinking, do not drive.
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Results are estimates for information only. Check important figures with a professional.