Blood Alcohol Content Calculator
Estimate blood alcohol concentration from drinks, body weight, sex and time.
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How to do it
- 1Fill in the boxes
Type your numbers or pick the options you need.
- 2See the result
The answer updates right away as you change a value.
- 3Use it
Copy the result or note it down. Nothing is sent anywhere.
About this tool
Enter the number of standard drinks (14 g of alcohol each), your weight, sex and the hours since you started. The tool uses the Widmark formula to estimate BAC and the hours needed to reach zero. It is an estimate only and must never be used to decide whether it is safe to drive.
How the estimate works
The Widmark formula divides the alcohol consumed by body weight and a distribution factor, about 0.68 for men and 0.55 for women, then subtracts about 0.015 percent per hour for elimination.
Why it is only a guide
Real BAC depends on food, medication, health, drink strength and how quickly you drink. Two people of the same weight can differ widely. Legal limits vary: 0.08 percent in most of the US and England, 0.05 percent in many European countries and Australia.
Safety
The only safe amount before driving is none. Use a taxi or a designated driver.
Frequently asked questions
What is a standard drink?
In the US, 14 g of pure alcohol: a 12 oz beer, 5 oz of wine or 1.5 oz of spirits.
How fast does the body clear alcohol?
About 0.015 percent BAC per hour, or roughly one drink an hour.
Is this accurate enough to drive on?
No. Never use an estimate to decide to drive.
What are the legal limits?
0.08 percent in the US and England, 0.05 percent in much of Europe and Australia, and lower for new drivers in some places.