What is a standard drink?

In the US, one standard drink contains 14 g of pure alcohol — roughly a 12 oz regular beer (5%), 5 oz wine (12%), or 1.5 oz distilled spirits (40%).

At what BAC is driving illegal?

In the US, Canada, and most of Europe, the legal limit for driving is 0.08% BAC. Some countries use 0.05%. Commercial drivers often face stricter limits of 0.04%.

How long does it take to sober up?

The body metabolizes alcohol at roughly 0.015% BAC per hour. At 0.08% BAC you need over 5 hours to reach zero. Coffee and cold showers do not speed this up.

Is this calculator accurate?

The Widmark formula provides an estimate. Actual BAC varies based on food intake, hydration, medications, liver health, and individual metabolism. Never rely on a calculator to judge fitness to drive.

Why does gender affect BAC?

Women generally have a lower body water ratio (r = 0.55 vs 0.68 for men), which means the same amount of alcohol is more concentrated in a woman's bloodstream.

Health

↵ to calculate

Blood Alcohol Content (BAC) Calculator

Estimate your blood alcohol content using the Widmark formula based on drinks consumed, body weight, and time elapsed.

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How to use this calculator

👉 Fill in the boxes below and your answer appears instantly — no maths needed, we do it all for you! 🎉

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In plain English — what does this do?

💚 A body helper! It tells you things about your health — like how much food you need, a healthy weight for your height, or when a baby might arrive. Easy to use, no doctor needed!

📌 Direct Answer & Summary

The Blood Alcohol Content (BAC) calculator estimates the concentration of alcohol in your bloodstream using the Widmark formula. BAC is expressed as grams of alcohol per 100 mL of blood. This calculator is for educational purposes only and should never be used to decide whether it is safe to drive.

Body Weight

Standard Drinks

Hours Since First Drink

What is Blood Alcohol Content (BAC) Calculator?

How to use it

1️⃣ Select your gender.
2️⃣ Enter your body weight and choose kg or lbs.
3️⃣ Enter the number of standard drinks consumed (one standard drink = 14 g of pure alcohol in the US).
4️⃣ Enter the number of hours since you started drinking.
5️⃣ Your estimated BAC appears instantly.

Formula

BAC = (drinks × 14) / (weight_g × r) − 0.015 × hours. Where r = 0.55 for women (body water constant) and r = 0.68 for men. Weight must be in grams.

💡 See it in action — a real example

A 70 kg (154 lb) man who drinks 3 standard drinks over 2 hours: BAC = (3 × 14) / (70000 × 0.68) − 0.015 × 2 = 42/47600 − 0.03 ≈ 0.058%. Below the legal limit, but judgment is still impaired.

❓ Common questions

What is a standard drink?: In the US, one standard drink contains 14 g of pure alcohol — roughly a 12 oz regular beer (5%), 5 oz wine (12%), or 1.5 oz distilled spirits (40%).
At what BAC is driving illegal?: In the US, Canada, and most of Europe, the legal limit for driving is 0.08% BAC. Some countries use 0.05%. Commercial drivers often face stricter limits of 0.04%.
How long does it take to sober up?: The body metabolizes alcohol at roughly 0.015% BAC per hour. At 0.08% BAC you need over 5 hours to reach zero. Coffee and cold showers do not speed this up.
Is this calculator accurate?: The Widmark formula provides an estimate. Actual BAC varies based on food intake, hydration, medications, liver health, and individual metabolism. Never rely on a calculator to judge fitness to drive.
Why does gender affect BAC?: Women generally have a lower body water ratio (r = 0.55 vs 0.68 for men), which means the same amount of alcohol is more concentrated in a woman's bloodstream.

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