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Blood Alcohol Calculator

Calculate your blood alcohol content (BAC / promil ‰) instantly based on your gender, weight, stomach fullness and the drinks you had. Based on the Widmark formula — no account needed.

A blood alcohol calculator estimates the alcohol concentration in your blood (‰) at a given moment. The tool below uses your weight, gender, stomach fullness and the drinks you've had to calculate your current BAC, compare it against the legal driving limit, and estimate how long until alcohol clears your system.

Enter Your Details

Stomach fullness affects the promil calculation

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Your Result

02.0
0.15‰

You are safe

1 hours 1 minutes until it resets

The promil values and time-until-below-the-limit estimates shown here are all approximate. Please don't drink alcohol for your health. Never drive under the influence of alcohol.

Legal Limit (Based on Your Location)

Detecting location...

Calories From Drinks

55 kcal

How Is Blood Alcohol Calculated?

What Is the Widmark Formula?

This tool is based on the Widmark formula, the method most widely used in forensic toxicology worldwide. It divides the amount of alcohol consumed (in grams) by the body's "water distribution volume" (weight × a coefficient that varies by gender) to estimate blood alcohol content (‰). Because men generally have a higher proportion of body water than women, the same amount of alcohol typically produces a lower BAC in men.

How Long Does Alcohol Stay in Your Body? Elimination Rate

A healthy liver metabolizes roughly ‰0.12-‰0.15 of alcohol per hour on average; this calculator uses ‰0.15. In people who drink heavily and regularly, this rate can rise to as much as ‰0.25 — but that doesn't mean sobering up faster; it means the liver is processing alcohol faster while the toll on the body is greater too. There's no way to speed up alcohol elimination — no coffee, cold shower, or trick works. Only time does.

Empty or Full Stomach? The Effect of Food

Alcohol is absorbed much faster on an empty stomach, producing a higher blood alcohol level; eating first slows absorption and keeps the peak level lower. That's why selecting your stomach fullness (empty, light, moderate, full) in the calculator directly affects the result.

Why Does Gender Change the Result?

On average, women's bodies contain less water and more fat tissue than men's; since alcohol distributes through body water rather than fat, the same weight and the same amount of alcohol typically produces a higher blood alcohol level in women than in men.

Does Age Affect the Calculation?

This tool uses the standard Widmark formula, the version most widely accepted in forensic/legal calculations, which doesn't use age as a numeric factor — it doesn't change the result directly. Age-related changes in liver function vary from person to person and aren't modeled in this general-purpose calculator.

Frequently Asked Questions

Promil (‰) is the unit used to express blood alcohol content — how many grams of alcohol are in one liter of blood. For example, 0.50‰ means 0.50 grams of alcohol per liter of blood.

Legal & Health Notice

This calculator produces an estimated value only and has no legal evidentiary value; a precise reading requires an approved breathalyzer or a blood test. Even below the legal limit, we recommend not driving after drinking, and not drinking for your health. This tool is not intended for users under 18.

Track Your Drinks in Real Time

With Promil Tracker, log every drink, watch your BAC update live, and see your history and stats. Completely free, no account required.