How long does alcohol stay in your system, and when can you drive after a party? It depends on what and how much you drank, your weight, height and sex, and whether you had eaten. So you don’t have to guess, we built a free alcohol calculator: it estimates your blood alcohol in per mille, shows the level of intoxication and tells you how many hours it takes to drop below Estonia’s 0.2 ‰ driving limit.
What the alcohol calculator shows
- Peak blood alcohol concentration in per mille and in exhaled breath (mg/l).
- Level of intoxication, from a mild effect to life-threatening alcohol poisoning.
- When you drop below 0.2 ‰ and when you are fully sober, in hours and as a clock time.
- Your current level if you enter how many hours have passed since you started drinking.
- Pure alcohol in grams and alcohol units (1 unit = 10 g).
You can add as many drinks as you need: beer, cider, long drinks, wine, sparkling wine, liqueur, vodka, whisky or any other drink with its own strength and volume.
How per mille is calculated
The calculator uses the Widmark formula: per mille = pure alcohol (g) / (weight × r). Pure alcohol is the drink volume × strength × 0.789 (the density of ethanol). The factor r is the share of body water, calculated with the Seidl formula from your sex, weight and height: about 0.7 for men and 0.6 for women on average. That is why a woman usually reaches a higher level after the same amount.
On an empty stomach about 90% of the alcohol is absorbed, after a meal about 70%, so the peak is lower and comes later.
How long does alcohol stay in your system?
The liver breaks alcohol down at a steady rate of about 0.15 per mille an hour. So 1 per mille takes roughly 6–7 hours to clear and 2 per mille about 13 hours. Coffee, a cold shower, exercise or sleep do not speed this up; they only make you feel more sober.
Example. A man, 80 kg, 180 cm, drinks two 0.5 l bottles of 5% beer on an empty stomach. He peaks at about 0.58 per mille, drops below 0.2 per mille after roughly 2.5 hours and is fully sober after about 4 hours.
Example. A woman, 60 kg, 165 cm, has two beers and three 40 ml vodkas after a meal. She peaks at about 1.36 per mille and needs more than 9 hours to sober up, so alcohol from the evening can still be in her blood the next morning.
Calculate your own level with the calculator.
Alcohol and driving in Estonia
- You are considered intoxicated from 0.2 per mille in the blood, or 0.1 mg/l in exhaled breath.
- From 1.5 per mille (0.75 mg/l) it is a criminal offence.
- “Morning-after” intoxication is common: if the party ended late, you can still be over the limit the next morning.
The calculator gives an estimate; it is not evidence and does not replace a breathalyser. If in doubt, do not drive: take a taxi or public transport.
Levels of intoxication
- 0.2–0.5 ‰: slower reactions; driving is already prohibited.
- 0.5–1.5 ‰: light intoxication, better mood, worse concentration.
- 1.5–2.5 ‰: moderate intoxication, slurred speech and poor coordination.
- 2.5–3.0 ‰: heavy intoxication, possible memory loss and loss of consciousness.
- over 3 ‰: alcohol poisoning, life-threatening. Call 112.
A calculator for your website
Calculators are among the most visited pages on a website: people search for them on Google, come back to them and share them. For a business it can be a price calculator, a loan or leasing calculator or a product configurator that brings in enquiries. We build these tools: price quote software, custom web applications and mobile apps. Write to us if you want a calculator on your website.
How long does alcohol stay in your system?
The body clears about 0.15 per mille an hour on average, so 1 per mille takes roughly 6–7 hours, though the rate varies from person to person.
How many per mille is one beer?
A 0.5 l bottle of 5% beer gives an 80 kg man about 0.3 and a 60 kg woman about 0.5 per mille. The calculator gives a more precise estimate.
When can I drive after drinking?
In Estonia only when your blood alcohol is below 0.2 per mille. Only a breathalyser can tell you for sure.
Does coffee or sleep help you sober up faster?
No. The liver breaks alcohol down at a steady rate and it cannot be sped up.
Open the alcohol calculator. It is free and your data is not saved.