Blood Alcohol (BAC) Calculator
Estimate your blood alcohol concentration (BAC %) from sex, weight and drinks consumed using the Widmark formula, and see when you fall below the limit.
Alcohol is absorbed ~25% faster on an empty stomach · metabolism slows at 65+
Time elapsed since you started drinking
What Is a Blood Alcohol Calculator and How Does It Work?
A blood alcohol calculator (or blood alcohol level calculator) estimates the concentration of alcohol in your blood (BAC — Blood Alcohol Concentration) using the scientific Widmark formula. This BAC calculator uses your sex, body weight, drink type, amount and time since drinking to show your estimated blood alcohol content as a percentage, then compares it against the legal limit and estimates how long until you sober up.
The Widmark formula:
- BAC = grams of alcohol ÷ (body weight kg × distribution factor) − (elimination rate × hours)
- Distribution factor: men → 0.68 | women → 0.55
- Alcohol in a drink = volume (ml) × ABV (%) × 0.789
For example, a 70 kg man who drinks a 500 ml beer (5%) over 2 hours: 19.7 g alcohol ÷ (70 × 0.68) − decline over time ≈ 0.017% BAC.
What Does BAC Mean? Blood Alcohol Concentration Explained
So, what does BAC mean? BAC is the percentage of alcohol in your blood — your blood alcohol content. 0.08% BAC means 0.08 grams of alcohol per 100 ml of blood. In traffic law, a driver's alcohol level is expressed as BAC. People begin to feel the effects of alcohol above about 0.01-0.03% BAC. High BAC values cause impaired coordination, delayed reaction, blurred vision, and above about 0.30% can lead to coma.
How Much Alcohol Is in One Beer? What BAC Does It Give?
How much alcohol is in one beer? A standard 500 ml beer at 5% ABV contains about 19.7 grams of pure alcohol. How much BAC that gives is the most asked question, and the answer depends on a person's weight and sex. The table below shows BAC results for a 500 ml 5% beer:
| Weight | Men (% BAC) | Women (% BAC) |
|---|---|---|
| 50 kg | 0.058 | 0.072 |
| 60 kg | 0.048 | 0.060 |
| 70 kg | 0.041 | 0.051 |
| 80 kg | 0.036 | 0.045 |
| 90 kg | 0.032 | 0.040 |
| 100 kg | 0.029 | 0.036 |
As you can see, the answer is not fixed. For a 60 kg woman, a single beer (0.060%) already exceeds a 0.05% limit. For two beers, double the values; for three beers, triple them. The tool does this automatically.
What BAC Does a Shot or a Glass of Wine Give?
Every drink has a different alcohol content, so its BAC differs:
- 1 single shot of spirits (45 ml, 40%): ~14 g alcohol → ~0.029% BAC in a 70 kg man
- 2 shots: ~28 g alcohol → ~0.058% BAC in a 70 kg man (over a 0.05% limit)
- 1 glass of wine (150 ml, 12%): ~14 g alcohol → ~0.029% BAC in a 70 kg man
- 1 tequila (45 ml, 38%): ~13 g alcohol → ~0.028% BAC in a 70 kg man
- 1 single whiskey (45 ml, 40%): ~14 g alcohol → ~0.029% BAC in a 70 kg man
These values are for right after drinking; the blood alcohol level drops by about 0.012% per hour as time passes. Use the drink list in the tool to get accurate results.
Legal BAC Limits — Country Comparison
The legal driving limit varies significantly from country to country:
- 0.00% (zero tolerance): Czech Republic, Hungary, Romania, Slovakia, UAE
- 0.02-0.035% (near zero): Poland (0.02%), Sweden (0.02%), Russia (0.035%)
- 0.02% (very low): Norway, Estonia, Japan
- 0.05%: Germany, France, Spain, Italy, Netherlands, much of the EU
- 0.08%: England, USA (federal), Canada, New Zealand
Professional drivers (trucks, buses, taxis) usually face a much lower limit. If you drive abroad, always check that country's BAC limit before getting behind the wheel.
How Long to Sober Up? How Much Does BAC Drop per Hour?
How long to sober up depends only on how much you drank, because the liver metabolizes about 0.012-0.015% BAC per hour, commonly taken as 0.012% per hour. To sober up completely from 0.08% BAC therefore takes roughly 6-7 hours. This rate is biologically fixed; the following do NOT lower BAC or help you sober up faster:
- Drinking coffee or espresso
- Energy drinks
- A cold shower
- Exercise
- Drinking lots of water
These may make you feel more awake but do not change the alcohol level in your blood. The only way to lower BAC is to wait. The "BAC Decline Timeline" in the tool shows the estimated value for each hour automatically.
Are Home Breathalyzers Reliable?
Consumer breathalyzers fall into two categories: cheap consumer devices and calibrated police-grade devices. Consumer devices can be used for reference, but results may deviate by ±15-20%. Official breath analyzers must be calibrated at regular intervals. For this reason a home breathalyzer result cannot be used for legal defense and should not be the sole basis for deciding whether to drive.
Alcohol and Health Effects After Drinking
A high blood alcohol level affects not only road safety but also general health. After drinking alcohol:
- Sleep quality drops: alcohol disrupts REM sleep; you do not wake up rested.
- The body loses water: alcohol is a diuretic and causes dehydration.
- The liver works: while metabolizing alcohol, the body cannot rest.
- Blood pressure rises temporarily: a large amount of alcohol strains the cardiovascular system.
- Blood sugar can drop: alcohol on an empty stomach raises the risk of hypoglycemia.
BAC Calculator — Frequently Asked Questions
This blood alcohol content calculator is an estimate, not a substitute for an official test. In the FAQ section below you can find answers to the most common questions about how much alcohol is in one beer, what BAC it gives, the legal BAC limit and how long it takes to sober up. Use this alcohol calculator responsibly — and never drink and drive.
Frequently Asked Questions About the Blood Alcohol (BAC) Calculator
A 500 ml 5% beer contains about 19.7 grams of pure alcohol. For a 70 kg man this gives roughly 0.041% BAC, and for a 60 kg woman roughly 0.060% BAC. Weight, sex and the time over which you drink change the result. The common legal driving limit is 0.08% (0.05% in many countries).
BAC (Blood Alcohol Concentration) is the amount of alcohol in your blood, usually expressed as a percentage. 0.08% BAC means 0.08 grams of alcohol per 100 ml of blood. In traffic law, a driver's alcohol level is measured as BAC.
The legal limit varies by country. 0.08% is common in the US, England, Canada and New Zealand. 0.05% is common across much of Europe (Germany, France, Spain, Italy). Some countries apply near-zero limits (0.00-0.02%). Professional drivers usually face a lower limit. Always check your local law.
The liver metabolizes about 0.012-0.015% BAC per hour, commonly taken as 0.012% per hour in a healthy adult. Coffee, energy drinks and cold water do not lower BAC; only time does. Waiting is the only thing that reduces your BAC.
A single 45 ml shot of 40% spirits contains about 14 grams of pure alcohol. For a 70 kg man this gives roughly 0.029% BAC. Two shots roughly double the value. A double measure contains about twice the alcohol of a single.
BAC is calculated with the Widmark formula: BAC = (grams of alcohol) / (body weight kg × distribution factor) − (elimination rate × hours). The distribution factor is 0.68 for men and 0.55 for women. The alcohol in a drink = volume (ml) × ABV (%) × 0.789. This tool applies the formula automatically.
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