Blood alcohol calculator
Health & fitnessHow much alcohol is in your blood?
A rough estimate of your blood alcohol in per mille (‰) and how long your body takes to clear it, by the Widmark formula.
What you enter stays on your device while you use this tool. Opening a shared link sends the settings in its address to HowToolbox to prepare the page.
Drink sizes: Beers 330 ml, 4.7% · Wine glasses 120 ml, 12.5% · Shots 40 ml, 40%
Estimated blood alcohol now
0.49 ‰
By this estimate, your body clears the alcohol in about 3 hours, 15 minutes.
Behind the estimate
- Highest level, if all alcohol were absorbed at once
- 0.64 ‰
- Alcohol in your drinks
- 24 g
- Time until the estimate reaches zero
- 3 hours, 15 minutes
Never use this estimate to decide whether you can drive. Your real level can be higher, and alcohol slows your reactions even below any legal limit. If you have been drinking, do not drive.
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Why your real level can differ
- The formula uses averages for body water and for how fast the liver burns alcohol. A real person can differ from them by a third or more in either direction.
- Food, the speed of drinking, medicines and your health change how fast alcohol is absorbed and cleared. Nothing speeds up the clearing: not coffee, sleep or a shower.
- If someone is very drunk, cannot be woken or breathes slowly, call the emergency number.
A rough estimate of your blood alcohol in per mille (‰) and how long your body takes to clear it, by the Widmark formula.
How to use
- Enter how many beers, glasses of wine and shots of spirits you have had.
- Enter the hours since your first drink, your weight and your sex.
- If your drinks were bigger or stronger, change their sizes and strengths.
- Read the rough estimate of your blood alcohol now and the time until it reaches zero.
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How it works
Alcohol spreads through the water in your body, so the same drinks give a smaller person, or a person with less body water, a higher level. The liver then removes it at a fairly steady pace, whatever you do.
The Swedish scientist Erik Widmark described this in 1932: ‰ = A ÷ (r × W) − β × t. A is the grams of alcohol (volume in ml × strength × 0.789 g/ml), W your weight in kg, r the share of your body the alcohol spreads into (on average 0.68 for men and 0.55 for women), β the rate the body clears it (about 0.15 ‰ an hour) and t the hours since you started. For example, two 330 ml beers of 4.7 % hold about 24 g of alcohol; for a 70 kg woman that is up to 0.64 ‰, about 0.49 ‰ an hour later, and zero after about four hours.
This is only a rough estimate for learning how alcohol works. Real levels vary widely from person to person and from day to day, and it must never be used to decide whether you can drive or are fit to do anything that needs a clear head.
Worked example
How many grams of alcohol are in 500 ml of beer at 5%?
- Alcohol volume: 500 × 5% = 25 ml.
That is about 19.7 g of alcohol. This amount alone does not tell you whether you are fit to drive.
Frequently asked questions
Can I use this to check whether I can drive?
No. The estimate can be far too low for you, and alcohol impairs driving even at small amounts. The only safe amount before driving is none, and the next morning you may still have alcohol in your blood.
Why do women get a higher estimate from the same drinks?
On average, women have less body water for their weight than men, so the same amount of alcohol is spread into less water and the concentration is higher. Widmark's factors 0.55 and 0.68 reflect that average.
Does coffee or sleep make the alcohol go faster?
No. The liver clears alcohol at its own pace, roughly 0.1 to 0.2 ‰ an hour. Coffee, a shower or sleep can make you feel more awake, but they do not lower the level.
Are all glasses of wine treated as the same size?
Only if you leave the serving size unchanged. Enter the actual volume and alcohol strength; drink counts alone do not describe the amount of alcohol.
Does a zero result prove there is no alcohol in my blood?
No. Zero is only where this simplified estimate bottoms out. It is not a measurement or proof that you are fit to drive.
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