Blood Alcohol and Driving in Germany: Limits, Elimination and the Formula

Which blood alcohol limits apply on German roads, how the Widmark formula estimates blood alcohol and why every calculation remains uncertain.

Health & Body1 linked calculatorsReading time: 5 min.

Guidance, not a diagnosis

This article explains reference values and where they come from. It does not replace a medical examination or advice. Different values often apply if you have symptoms, are pregnant, for children and for pre-existing conditions: in that case, talk to your doctor.

Germany measures blood alcohol in per mille: 1 per mille means 1 gram of alcohol per kilogram of blood. How high the value is after a few drinks can be estimated with the Widmark formula. Such an estimate is never enough to decide whether you can still drive.

Key takeaways

  • In a car, 0.5 per mille is an administrative offence (section 24a StVG); from 1.6 per mille the authority orders a medical-psychological assessment (section 13 FeV).
  • During the probationary period and before the age of 21, drivers must not drink any alcohol (section 24c StVG).
  • The Widmark formula divides the amount of alcohol by body weight and a distribution factor; our calculator then subtracts 0.15 per mille per hour.
  • Even below the limits, anyone who can no longer drive safely because of alcohol commits a criminal offence (section 316 StGB).

Blood alcohol limits on the road

The consequences of a given value are set out in the Road Traffic Act, the Driving Licence Ordinance and the Criminal Code:

Blood alcoholWhat appliesLegal basis
any value above 0administrative offence for drivers in their probationary period and everyone under 21 driving a motor vehicleSection 24c StVG
0.5 per mille or moreadministrative offence when driving a motor vehicleSection 24a StVG
1.6 per mille or moremedical-psychological assessment if a vehicle was driven with this valueSection 13 FeV
no fixed valuecriminal offence if someone drives a vehicle although alcohol means they can no longer drive it safelySection 316 StGB

Below the limit is not a free pass

The limits describe when a consequence applies without further proof. Anyone who drives unsafely or causes an accident with less alcohol can still be punished. The only safe rule: if you drive, don't drink.

How the Widmark formula estimates blood alcohol

The formula goes back to the Swedish chemist Erik Widmark and works in three steps:

  1. Alcohol in grams: volume in ml × alcohol content in percent ÷ 100 × 0.8 (density of alcohol in g/ml, rounded).
  2. Distribution in the body: the amount of alcohol is divided by body weight × distribution factor. The factor reflects that alcohol spreads only through body water.
  3. Elimination: from the end of drinking, the value falls by a fixed amount every hour.

Our calculator assumes a distribution factor of 0.7 for men and 0.6 for women and an elimination of 0.15 per mille per hour. These are calculation assumptions, not legally or medically fixed values; the actual course differs from person to person.

Worked example: two beers

A man weighing 80 kg drinks 2 bottles of beer, each 500 ml with 5% alcohol. That is about 40 g of alcohol. According to Widmark this gives roughly 0.71 per mille. At the assumed elimination rate it takes about 5 hours until the value is back at 0.

Estimate blood alcohol for your drinks

Add your drinks, enter weight and time: the calculator shows the estimated course.

Calculate now

Why every calculation is only an estimate

The formula gives an average. In an individual case, actual blood alcohol differs, mainly for three reasons:

  • How quickly alcohol enters the blood depends on whether and what you have eaten and how fast you drink.
  • Build and body water differ more than a single factor can reflect.
  • Elimination is not equally fast in everyone.

That is why no calculation, including our calculator, is suitable for deciding whether you can drive. It helps you understand how long alcohol stays in the body.

Frequently asked questions about blood alcohol

Do the limits apply on a bicycle too?
The 0.5 per mille limit of section 24a StVG applies to motor vehicles. However, under section 316 StGB anyone who rides any vehicle, including a bicycle, although alcohol means they can no longer ride it safely, commits an offence. And anyone who drove a vehicle with 1.6 per mille or more must expect a medical-psychological assessment under section 13 FeV.
How fast does the body eliminate alcohol?
There is no legally fixed value, and elimination varies from person to person. Our calculator assumes 0.15 per mille per hour. After heavy drinking it takes correspondingly many hours until the value reaches 0.
Can I still have alcohol in my blood the next morning?
Yes. If you go to bed with 1.0 per mille, for example, the assumed elimination rate means you would still have alcohol in your blood for about 7 hours. Sleep does not speed up the calculation.
What do values in mg/l mean?
That is breath alcohol as measured by a device. The law names it alongside blood alcohol: in section 24a StVG, 0.25 mg/l corresponds to the 0.5 per mille limit, and in section 13 FeV, 0.8 mg/l corresponds to 1.6 per mille.

Sources

Every figure in this article comes from these primary sources or from the linked calculators, which are based on the same sources.

  1. Section 24a Road Traffic Act (StVG, 0.5 per mille limit) (accessed September 30, 2026)
  2. Section 24c Road Traffic Act (StVG, alcohol ban for new drivers) (accessed September 30, 2026)
  3. Section 13 Driving Licence Ordinance (FeV, medical-psychological assessment) (accessed September 30, 2026)
  4. Section 316 Criminal Code (StGB, driving while intoxicated) (accessed September 30, 2026)
Onur Cirakoglu — Full-Stack Developer & Founder of HEADON.pro
Onur CirakogluSources verified

Full-Stack Developer & Founder of HEADON.pro

Full-stack developer and founder of HEADON.pro. Developer of Rechnerzentrale.