Real drinks, not a rough count
A strong beer is not the same as a light one. Therefore each drink has its own size and strength, and you can edit both.
Free estimate, nothing uploaded
BAC CalculatorEstimate Your Blood Alcohol Content and Time to Sober
Estimate your blood alcohol content in seconds with this free BAC calculator. Add your drinks with their real sizes and strengths, then enter your weight and the time since your first drink. You will see your estimated BAC, how it compares with the legal limit and when it should return to zero.
- Widmark formula
- Real drink sizes and strengths
- Clock time to sober
- Metric and US units
Blood alcohol calculator
Biological sex
Units
Your drinks0 g of alcohol
0 to 24
0.000% BAC
No alcohol entered
0.00 per mille, 0 mg per 100 ml
Add your drinks to see an estimate.
- Under 0.08%–
- Under 0.05%–
- Under 0.03%–
- Back to 0.00%–
- Alcohol0 g
- US std drinks0.0
- Peak BAC0.000%
Estimate only. Never use this result to decide whether to drive.
Please read this. This BAC calculator gives an estimate for education only. Real blood alcohol levels vary with food, health, medication and how fast you drink, so your true level can be higher. Never use it to decide whether you are safe or legal to drive. If you have been drinking, do not drive.
Features
Why This BAC Calculator Is Better
Many calculators ask for a single number of drinks and return a bare percentage. This one starts from what you actually drank and tells you what the number means.
Clock times, not just hours
The result shows the time on the clock when your estimate should fall below 0.08%, 0.05%, 0.03% and back to zero.
Legal limits for many countries
Pick the United States, India, the UK, Australia and more. The tool then compares your estimate with that limit and explains the gap.
Metric and US units
Switch between kilograms with millilitres and pounds with fluid ounces. Your weight and every drink convert instantly.
Three ways to read the result
See your BAC as a percentage, in per mille and in milligrams per 100 ml. As a result, it matches the units used where you live.
Open about its limits
The method is shown on this page and the tool says clearly what it cannot know. Meanwhile, nothing you enter leaves your browser.
Step by step
How to Use the BAC Calculator
The estimate updates as you type, so there is no calculate button.
Enter your sex and weight
Choose male or female and type your body weight. Both change how much the alcohol is diluted in your body.
Add your drinks
Tap Beer, Wine or Spirits for each drink, then set how many you had. Next, adjust the size and strength if your drink was different.
Set the time
Enter the hours since your first drink. The calculator subtracts the alcohol your body has already cleared.
Read your estimate
Check the gauge, the comparison with your legal limit and the clock times. Then plan a safe way home.
What the number means
BAC Levels and Their Typical Effects
Alcohol affects people differently, but road safety agencies describe a common pattern as blood alcohol content rises.
| BAC | Typical effects |
|---|---|
| 0.02% | Relaxed mood and a slight loss of judgement |
| 0.05% | Lower alertness, weaker coordination and slower responses |
| 0.08% | Poor muscle control and impaired judgement, reasoning and memory |
| 0.10% | Clearly slower reactions, slurred speech and reduced control |
| 0.15% | Major loss of balance, and vomiting may occur |
| 0.30% | Confusion and a risk of passing out |
| 0.40% and above | Risk of coma and death |
If someone is confused, cannot be woken or is breathing slowly after drinking, call your local emergency number straight away.
Know the law
Legal Drink-Drive Limits by Country
The legal limit depends on where you drive. These are the general limits for car drivers, shown as BAC and in milligrams per 100 ml of blood.
| Where | Limit as BAC | mg per 100 ml |
|---|---|---|
| United States, most states | 0.08% | 80 |
| Utah, USA | 0.05% | 50 |
| Canada | 0.08% | 80 |
| England, Wales and Northern Ireland | 0.08% | 80 |
| Scotland, Ireland | 0.05% | 50 |
| Australia, New Zealand | 0.05% | 50 |
| Germany, France, Italy | 0.05% | 50 |
| India, Japan | 0.03% | 30 |
| China, Sweden, Norway, Poland | 0.02% | 20 |
| Brazil, Czech Republic, Hungary | 0.00% | 0 |
Laws change, and many places set lower limits for new, young and commercial drivers. England and Wales are also consulting on a lower limit of 0.05%. Always check the current rule where you drive.
The method
How the BAC Calculator Works
The tool uses the Widmark formula, which has been the standard way to estimate blood alcohol content for about a century.
The Widmark formula
BAC % = alcohol in grams ÷ (body weight in grams × r) × 100 − 0.015 × hoursThe ratio r is 0.68 for men and 0.55 for women. The last part removes about 0.015% for every hour since your first drink, which is the average rate at which the body clears alcohol.
Grams of alcohol in a drink
grams = volume in ml × ABV % ÷ 100 × 0.789A US standard drink holds 14 g of alcohol, a UK unit holds 8 g and an Australian standard drink holds 10 g. For example, a 330 ml beer at 5% contains about 13 g.
Benefits
What a BAC Estimate Helps You Do
A blood alcohol estimate will not tell you that you are safe to drive. However, it is a useful guide for planning and for learning.
Plan a safe way home
Run the numbers before a night out. If the estimate is anywhere near the limit, book a taxi or agree on a driver who will not drink.
Pace your drinks
See how each extra drink moves the gauge. In addition, alternate with water and check your daily target with the water intake calculator.
Understand the morning after
Alcohol can stay in your blood long after you stop. The clock times show whether you may still be over the limit at breakfast, even after a full night planned with the sleep calculator.
Learn what a standard drink is
Large glasses and strong beers often count as two drinks or more. The totals show the real amount of alcohol in grams.
Compare limits when you travel
A level that is legal in one country can be an offence in the next. Switch the limit to see the difference before you go.
Teach and talk about alcohol
Parents, teachers and trainers can use the gauge to show how weight, sex and time change the result. Because it is visual, the lesson sticks.
FAQ
BAC Calculator Questions and Answers
What is BAC?
BAC stands for blood alcohol content, also called blood alcohol concentration. It is the amount of alcohol in your blood, written as a percentage. A BAC of 0.08% means 0.08 grams of alcohol in every 100 millilitres of blood, which is the same as 80 mg per 100 ml.
How does a BAC calculator work?
A BAC calculator adds up the grams of alcohol in your drinks and divides them by your body weight and a ratio for your sex. It then subtracts about 0.015% for each hour since your first drink. This method is known as the Widmark formula.
How long does it take for BAC to return to zero?
The body clears alcohol at about 0.015% per hour on average. From 0.08% that takes a little over five hours, and from 0.15% it takes about ten hours. The calculator shows the clock time for your own numbers.
How many drinks does it take to reach 0.08%?
It depends on your weight and sex. For example, an 80 kg (176 lb) man who has four standard drinks in two hours is at about 0.07%. Meanwhile, a 60 kg (132 lb) woman who has three is at about 0.10%. Use the calculator for your own numbers.
Can coffee, food or a cold shower lower BAC?
No. Only time lowers BAC. Coffee and showers can make you feel more awake, but your liver still clears alcohol at the same rate. Eating before you drink slows absorption, yet it does not remove alcohol that is already in your blood.
Can I use this BAC calculator to decide if I can drive?
No. The result is an estimate, and your real level can be higher. Impairment also begins well below the legal limit. If you have been drinking, arrange a taxi, a lift or a place to stay.
Why do women usually reach a higher BAC than men?
On average, women have less body water than men of the same weight, so the same amount of alcohol is less diluted. The formula reflects this with a ratio of 0.55 for women and 0.68 for men.
What is the legal BAC limit in India and the United States?
India's limit is 0.03%, or 30 mg of alcohol per 100 ml of blood. In the United States the limit is 0.08% in every state except Utah, where it is 0.05%. Lower limits often apply to commercial drivers and to drivers under 21.
Check Your Estimate, Then Plan a Safe Ride
This BAC calculator turns your drinks, weight and time into a clear estimate with real clock times. Use it to plan ahead, and remember that the only safe level for driving is zero.
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