Current for 2026•As of: July 2026

Blood Alcohol Calculator calculate BAC.

Widmark formula with elimination over time – for information only, not proof of fitness to drive

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Blood Alcohol Calculator

Calculate blood alcohol using the Widmark formula – for information only.

Gender

30 kg200 kg
0 ml1,000 ml
0 %60 %

Beer: ~5% · Wine: ~12% · Sparkling wine: ~11% · Spirits: ~40%

0 hrs24 hrs

Elimination rate: approx. 0.15‰ per hour

BAC after drinking

0.36 ‰

Alcohol: 20.0 g

Alcohol (g)20.0 g
BAC directly0.36 ‰
After 0 hour(s)0.36 ‰

Not proof of fitness to drive: This calculator makes no statement whatsoever about fitness to drive and does not replace a fitness-to-drive test. The calculated value is a theoretical estimate – individual factors such as fatigue, tolerance, medication, stomach contents and metabolism can vary considerably. Never drive under the influence of alcohol.

Medical note: The Widmark formula is an approximation and does not account for absorption time, stomach contents or individual enzyme activity. Actual blood alcohol concentrations can deviate considerably. This calculator is for informational purposes only.

Blood alcohol and drinking: what the calculator computes

Widmark formula, elimination and limits of the calculation

The blood alcohol calculator computes a theoretical blood alcohol concentration (BAC) using the scientifically recognized Widmark formula, named after the Swedish physician Erik Widmark (1922). The formula uses three inputs: the amount of alcohol consumed in grams, body weight, and the gender-specific distribution factor r (0.7 for men, 0.6 for women). The result is a calculated estimate that can deviate significantly from the actual blood alcohol concentration.

The amount of alcohol in grams is calculated as: volume (ml) × alcohol content (vol%) / 100 × 0.8 g/ml (density of ethanol). Example: a 500 ml beer with 5 vol% contains 500 × 0.05 × 0.8 = 20 grams of pure alcohol. For an 80 kg man, that results in: 20 / (80 × 0.7) ≈ 0.36‰. This value is reduced over time as the liver breaks down the alcohol. The average elimination rate is 0.15‰ per hour. After 2 hours, that would be about 0.06‰.

It is essential to understand the limitations of this calculator: the Widmark formula does not account for absorption delay caused by food in the stomach, individual enzyme activity (alcohol dehydrogenase), alcohol tolerance from regular consumption, interactions with medication, or variations caused by illness or hormonal status. In reality, actual BAC is often 10–20% below the calculated value (absorption deficit), but can also be higher when drinking on an empty stomach. The calculator therefore provides only a rough estimate, not a reliable measured value.

One particularly important note: alcohol impairs fitness to drive starting at very low levels – well below the legal 0.5‰ limit in Germany. Reaction time, risk-taking, lane-keeping and hazard perception are measurably impaired starting at just 0.2‰. This calculator makes no statement whatsoever about whether someone is fit to drive. When in doubt: do not drive, use public transport or call a taxi.

Alcohol content of typical drinks

Alcohol in standard drinks (approx.)

Beer (500 ml, 5 vol%)
Approx. 20 g pure alcohol. Roughly one "standard drink".
Wine (200 ml, 12 vol%)
Approx. 19 g pure alcohol. A small glass of red wine.
Sparkling wine (150 ml, 11 vol%)
Approx. 13 g pure alcohol. One glass of sparkling wine.
Spirits (40 ml, 40 vol%)
Approx. 13 g pure alcohol. One shot.
Alcopops (330 ml, 5 vol%)
Approx. 13 g pure alcohol. High in sugar.
Non-alcoholic beer (500 ml, 0.5 vol%)
Approx. 2 g pure alcohol. Significantly less alcohol.

Calculation example

80 kg man: 500 ml beer (5 vol%)

80 kg man: 500 ml beer (5 vol%)
ItemAmount
Alcohol: 500 × 0.05 × 0.820 g
BAC = 20 / (80 × 0.7)≈ 0.36‰
After 2 h (−0.30‰)≈ 0.06‰
Fitness to driveNo statement possible

Frequently asked questions about the blood alcohol calculator

Widmark formula, elimination and legal limits

The Widmark formula calculates the theoretical blood alcohol concentration (BAC) from the amount of alcohol consumed and body weight. First, the alcohol mass in grams is calculated: volume (ml) × alcohol content (vol%) / 100 × 0.8 (density of ethanol). This amount is divided by the product of body weight (kg) and the Widmark factor r (0.7 for men, 0.6 for women). The result is the theoretical BAC in per mille. The formula assumes ideal conditions and does not account for absorption delay caused by food.

The human body breaks down alcohol at an average rate of about 0.1–0.2‰ per hour. The average value of 0.15‰/hour is a commonly used approximation. Women tend to break down alcohol slightly more slowly than men. Influencing factors include liver condition, nutritional status, genetics (enzyme profile) and alcohol tolerance level. Being on an empty stomach speeds up absorption, but not elimination. Coffee, exercise or a cold shower have no effect on the elimination rate.

In Germany, drivers of cars are subject to the 0.5 per mille limit (§ 24a StVG). From 0.5‰ with signs of impairment (swerving, accident) or from 1.6‰, unfitness to drive is considered absolute (§ 316 StGB). For learner drivers and drivers under 21, a 0.0 per mille limit applies. Our calculator computes purely theoretical estimates and makes no statement about fitness or capability to drive. Individual impairment varies considerably and can begin well below the legal limit.

Women have a lower Widmark factor (r = 0.6) than men (r = 0.7), because women on average have a higher body fat percentage and less body water. Since alcohol distributes through body water, the same amount of alcohol leads to a higher blood alcohol concentration in women. In addition, women often have lower activity of the enzyme alcohol dehydrogenase in the stomach lining, which reduces the first breakdown stage in the stomach (so-called first-pass metabolism).

This depends on the amount of alcohol consumed and your body weight. With an elimination rate of 0.15‰/hour, it takes about 6–7 hours for 1.0‰ to be fully broken down. For 2.0‰, that corresponds to 13–14 hours. Sleep does not speed up elimination. Important: even at 0‰, residual effects such as slowed reaction time and concentration problems can still be present (so-called hangover effect). For driving decisions: when in doubt, do not drive.

Important note

These calculations are for non-binding information only and do not replace professional tax advice. All information without guarantee. Learn more

Sources & calculation basis

Our calculations are based on the following official sources (as of: July 2026):

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