Blood Alcohol Calculator: BAC from Beers & Pegs

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📘 About the Blood Alcohol Calculator

Blood alcohol concentration (BAC) is the amount of alcohol in your blood. This calculator uses the Widmark formula: grams of alcohol ÷ (body weight × 0.68 for men or 0.55 for women), less about 0.015% for every hour your liver works on it.

India's legal limit for driving is 30 mg per 100 ml of blood (0.03%) — about one large beer for many people. Food, body fat, medicines and tiredness change your real level, so treat the result as a rough guide: the only safe amount before driving is none.

✏️ Worked examples

3 small whisky pegs, 70 kg man, 2 hours

You enter
Your weight	70 kg
Sex	Male
Hours since your first drink	2 h
Driving limit to compare with	India — 30 mg/100 ml
Whisky / rum / vodka / gin — small peg (30 ml)	3

You get
Estimated blood alcohol now	0.149% (149 mg/100 ml)
How you may feel	Clearly drunk — poor balance, slurred speech, slow reactions
Legal driving limit — India	0.03% (30 mg/100 ml)
Over the limit?	YES — do not drive
Time until below the limit	7 h 56 min more
Time until alcohol is gone	about 9 h 56 min
Alcohol drunk	82 g (8.2 standard drinks of 10 g) — 2 × Beer, large bottle, 3 × Whisky / rum / vodka / gin — small peg

BAC 0.149% (149 mg/100 ml); YES — do not drive.

2 large beers (650 ml), 60 kg woman, 1 hour

You enter
Your weight	60 kg
Sex	Female
Hours since your first drink	1 h
Driving limit to compare with	India — 30 mg/100 ml
Beer — large bottle (650 ml, 5%)	2

You get
Estimated blood alcohol now	0.148% (148 mg/100 ml)
How you may feel	Clearly drunk — poor balance, slurred speech, slow reactions
Legal driving limit — India	0.03% (30 mg/100 ml)
Over the limit?	YES — do not drive
Time until below the limit	7 h 52 min more
Time until alcohol is gone	about 9 h 52 min
Alcohol drunk	51 g (5.1 standard drinks of 10 g) — 2 × Beer, large bottle

BAC 0.148% (148 mg/100 ml); below the limit in 7 h 52 min more.

🧭 How to use this calculator

What you enter

Your weight (kg)
Sex
Hours since your first drink (h)
Driving limit to compare with
Beer — can / small bottle (330 ml, 5%)
Beer — large bottle (650 ml, 5%)
Beer — pint / 500 ml can (5%)
Strong beer — large bottle (650 ml, 8%)
Strong beer — 500 ml can (8%)
Whisky / rum / vodka / gin — small peg (30 ml)
Whisky / rum / vodka / gin — large peg (60 ml)
Wine — glass (150 ml)
Breezer / ready-to-drink (275 ml)
Shot (45 ml, 40%)
Other drink — amount (ml)Optional: any other drink, with its alcohol % below.
Other drink — alcohol (%)

What you get

Estimated blood alcohol now
How you may feel
Legal driving limit — India
Over the limit?
Time until below the limit
Time until alcohol is gone
Alcohol drunk

💡 Safety first

Never drive, ride or swim after drinking — plan a cab or a sober driver.
Signs of alcohol poisoning: confusion, vomiting, seizures, slow or irregular breathing, blue or pale skin, can't be woken. Call 108 (India) or your emergency number.
Do not mix alcohol with sleeping pills, painkillers or other medicines.
Drinking water and eating slows absorption but does not lower the total alcohol in your blood.

❓ Frequently asked questions

How many beers can I drink and drive in India?

There is no safe number. The limit is 30 mg/100 ml, and a single 650 ml bottle of 5% beer can put a 60 kg man above it for the first hour or two. Use a cab or a designated driver.

How long does it take for alcohol to leave the body?

On average the liver removes about 0.015% BAC per hour — roughly one small peg or one 330 ml beer an hour. Coffee, a cold shower or sleep do not speed it up.

What is a peg?

In India a small peg is 30 ml and a large (Patiala) peg is 60 ml of whisky, rum, vodka or gin at 42.8% alcohol. A 30 ml peg has about 10 g of pure alcohol — one standard drink.

🍺 Blood Alcohol Calculator (BAC) by Beers, Pegs & Glasses