BAC Calculator

Estimate blood alcohol concentration from drinks, body weight, sex, time, and alcohol content.

Estimated BAC

0.1%

Widmark-style estimate

Alcohol consumed

42 g

Pure alcohol estimate

Time to near zero

3.5 hr

Rough metabolism estimate

Safety note

Do not drive

BAC estimates are uncertain

BAC inputs

Estimate blood alcohol concentration from drink size, ABV, weight, sex estimate, and time.

Weight

Sex estimateDrinks

Drink size

ABV

Hours since first drink

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What is the BAC calculator?

BAC, or blood alcohol concentration, measures the percentage of alcohol in the blood. This calculator estimates BAC from body weight, sex, food intake, alcohol volume, alcohol percentage, and elapsed time.

Korea treats BAC 0.03% or higher as drunk driving. The result is a medical estimate, not a legal measurement, so it should be used to avoid driving rather than to decide whether driving is acceptable.

Widmark formula and Korean thresholds

Calculation method

The calculator uses the Widmark formula developed by Erik Widmark.
BAC (%) = alcohol grams / (body weight kg x sex distribution factor) x 100 - elapsed hours x alcohol elimination rate.
Sex distribution factors are 0.68 for men and 0.55 for women in the Korean source.
Alcohol elimination is modeled at about 0.015% per hour, with individual variation.
Alcohol grams = beverage volume in mL x alcohol percentage x alcohol density 0.7894.

Korean drunk-driving standards

BAC 0.03% to under 0.08%: license suspension, up to 1 year imprisonment or fine up to KRW 5,000,000.
BAC 0.08% to under 0.2%: license revocation, 1 to 2 years imprisonment or fine from KRW 5,000,000 to KRW 10,000,000.
BAC 0.2% or higher: aggravated punishment, 2 to 5 years imprisonment or fine from KRW 10,000,000 to KRW 20,000,000.
Refusing a breath test can lead to 1 to 6 years imprisonment or fine from KRW 5,000,000 to KRW 30,000,000.

Practical examples and safety

Soju and overnight driving examples

One 360 mL bottle of soju at 16.5% contains about 46.9 g of pure alcohol.
For a 70 kg man, that amount can create an estimated BAC around 0.098%, above the 0.08% license-revocation threshold.
A 70 kg man drinking one bottle of soju may need about 7 to 8 hours before BAC falls below 0.03%.
Coffee, water, vomiting, or a shower may improve alertness or comfort but do not meaningfully speed alcohol metabolism.

Health drinking guide

The Korean content references WHO-style moderate drinking limits: up to 2 drinks, or 40 g alcohol, per day for men and 1 drink, or 20 g, per day for women.
Drinking on an empty stomach can raise absorption speed 2 to 3 times.
Drinking slowly, alternating with water, avoiding mixed high-proof drinks, and keeping at least two alcohol-free days per week all reduce risk.
Medication interactions, liver health, body composition, age, and fatigue can make actual BAC higher than the estimate.