When can I drive after drinking?

Sex

Weight (kg)

Drink strength (%)

Volume (ml)

Drinking duration (hours)

Food consumed while drinking

BAC estimate

Pure alcohol consumed: 19,73 g
Peak estimate: 0,36 ?
Current estimate: 0,06 ?
Estimated time to 0.0: 0,42 h

If you are trying to estimate when you may be sober, use the time to 0.0 as a rough guide and leave extra margin.

Important: this is an estimate only, not legal or medical advice.

What the Widmark formula suggests, and why it cannot be trusted to the decimal

Estimate blood alcohol concentration from drinks, body weight and time elapsed using the Widmark formula. An estimate only — never a driving decision.

This applies the Widmark equation: alcohol consumed, divided by body weight and a distribution factor, minus what your liver has processed since the first drink.

Treat the number as an order of magnitude, not a measurement. Real BAC depends on food, sex, medication, liver function, hydration and drinking speed — variation between two people with identical inputs can easily be 30% or more.

What this calculator shows

Estimated grams of alcohol consumed
Approximate peak and current BAC
A rough time until alcohol would clear at an average elimination rate

What to keep in mind

Elimination is assumed at roughly 0.15‰ per hour, which varies substantially between individuals.
This is not a legal or medical instrument. If you have been drinking, do not drive — no calculator can tell you that you are safe.

FAQs

Can I use this to decide whether to drive?

No. It is an estimate with wide error bars, and the only safe rule after drinking is not to drive. Police tests measure you, not an average person.

Does coffee or a cold shower speed things up?

Neither. The liver processes alcohol at its own pace. Caffeine can make you feel more alert while leaving you just as impaired, which is arguably more dangerous.

Why do men and women get different results?

Body water distribution differs on average, so the same alcohol reaches a higher concentration. The formula uses different factors, but individual variation is still large.

Does eating first change the outcome?

Food slows absorption, so the peak is lower and later. It does not reduce the total amount your body must process.

Worked example

Half a litre of beer

Input: 500 ml at 5%, 80 kg, two hours elapsed

Output: Roughly 0.2‰ remaining

Note: Many countries set the limit at 0.5‰ and some at 0.0‰. Being under an estimate is not evidence of being under the limit.

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When can I drive after drinking?

BAC estimate

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