Can I use this to know if I'm safe to drive?

No. Real BAC varies widely with food, medications, metabolism and pour sizes, and impairment starts well below the legal limit. If you've been drinking, don't drive.

BAC Calculator

Estimate blood alcohol content from drinks, weight and time — with clear safety warnings.

Body WeightUnitStandard DrinksHours Since First Drink

1 standard U.S. drink ≈ 12 oz beer (5%), 5 oz wine (12%) or 1.5 oz spirits (40%).

Estimated BAC

0.046%

Mild impairment

3.0 h

Approx. Hours to 0.000%

0.08%

U.S. Legal Driving Limit

Warning: This is a rough estimate only — real BAC varies widely with food, metabolism, medications and drink strength, and impairment starts well below 0.08%. Never use this to decide whether you can drive. If you've been drinking, don't drive — period. Not medical or legal advice.

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What Is the BAC Calculator?

The BAC Calculator estimates blood alcohol concentration using the Widmark formula from your weight, sex, standard drinks consumed and hours elapsed. It shows the estimated level, what it typically means for impairment, and roughly how long until you're back to zero. Everything is calculated locally.

How It Works

Enter your details and drinks. One standard U.S. drink is 12 oz of 5% beer, 5 oz of wine or 1.5 oz of spirits.

When to Use It

Use it for education — understanding how drinks, body weight and time interact. Never use it to decide whether you can drive.

Frequently Asked Questions

Can I use this to know if I'm safe to drive?: No. Real BAC varies widely with food, medications, metabolism and pour sizes, and impairment starts well below the legal limit. If you've been drinking, don't drive.

Found an issue? Send Feedback. See our data sources and update policy for tools that depend on changing information.