Blood Alcohol Content (BAC) Calculator
Estimate your blood alcohol content (BAC) based on drinks consumed, weight, gender, and time.
About this calculator
Blood alcohol concentration, or BAC, is the share of alcohol in your blood. This calculator estimates it from your weight, sex, the number of standard drinks and the hours since you started, using the Widmark formula, and gives a rough time until you are sober.
Treat the result as an educational estimate only. Real BAC depends on food, medication, health, drink strength and individual metabolism, and impairment starts well below the legal limit. Never drive after drinking. The only safe level to drive is zero, and in India the limit is 0.03% (30 mg per 100 ml of blood).
How to use it
- Enter your Weight and choose your Gender.
- Enter the number of Drinks, the Hours since you started and the Drink Type.
- Press Estimate BAC and read the estimated level and time to sober.
Widmark formula
BAC % = (Alcohol grams ÷ (Weight(g) × r)) × 100 − 0.015 × hours. One standard drink is taken as 14 g of pure alcohol. The distribution ratio r is 0.68 for men and 0.55 for women. The body removes about 0.015% BAC per hour. Time to sober is BAC ÷ 0.015 hours.
Worked example
Man, 70 kg, 3 drinks over 2 hours
| Estimated BAC | 0.058% |
| Time until sober | about 3.9 hours |
That is nearly double India's 0.03% limit for drivers. Coffee, cold showers and fresh air do not speed up sobering. Only time does.
This tool gives general information, not medical advice. Talk to a doctor before making health decisions.
Tips and common mistakes
- Never drive, ride or operate machinery after drinking. Book a cab or nominate a sober driver.
- Food slows absorption, but it does not stop impairment.
- Women usually reach a higher BAC than men from the same drinks, because of body water differences.
- Strong drinks, mixers with caffeine and an empty stomach all raise risk.
- If someone is unconscious, vomiting or breathing slowly after drinking, call emergency services.
Frequently asked questions
What is the legal BAC limit in India?
0.03%, or 30 mg of alcohol per 100 ml of blood, under the Motor Vehicles Act.
How long does alcohol stay in the body?
The body clears about 0.015% BAC an hour, so each drink takes roughly an hour.
What counts as a standard drink?
About 330 ml of beer, 150 ml of wine or 45 ml of spirits, each around 14 g of alcohol.
Can I sober up faster?
No. Coffee, water and showers do not change how fast the liver works.
How accurate is the calculator?
It is a rough estimate that can be off by a wide margin. Do not use it to decide whether to drive.
Why does sex matter?
Women on average have less body water, so the same alcohol is more concentrated.