Toolorio

BAC Calculator

Enter your details below to get a rough estimate of blood alcohol content (BAC) using the Widmark formula. This is not a substitute for a breathalyzer and should never be used to decide whether it's safe to drive.

One standard drink ≈ 14g of alcohol (a 355ml beer, 148ml glass of wine, or 44ml shot of spirits).

0.021%Minimal impairment

This tool does not measure legal intoxication. Never drive after drinking, regardless of the estimate shown.

This estimate uses the simplified Widmark formula and ignores factors like food, metabolism and medication — actual BAC can differ significantly. For entertainment and educational purposes only, not a medical or legal device.

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How to use

  1. Choose metric or imperial units, then enter your sex and weight.
  2. Enter the number of standard drinks consumed and hours since your first drink.
  3. Read the estimated BAC percentage — treat it only as a rough educational estimate.

What is this tool?

BAC Calculator applies the Widmark formula, a simplified model that estimates blood alcohol concentration from body weight, sex-based distribution ratio, alcohol consumed and elimination rate over time. It's widely taught as an educational approximation, but doesn't account for individual factors like food intake, medications, liver function or genetics that significantly affect real BAC.

Common uses

  • Learning how factors like weight and time affect blood alcohol estimates
  • Educational demonstrations of the Widmark formula
  • Getting a rough sense of how alcohol may still be affecting the body
  • Classroom or training material on alcohol metabolism

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FAQ

Can I use this to decide if I'm okay to drive?

No. Never use this or any estimate to decide whether to drive after drinking. The only safe choice after drinking is not to drive — actual impairment and legal BAC can differ significantly from this estimate.

Why might my actual BAC differ from the estimate?

Food intake, drinking speed, medications, liver function, hydration and genetics all affect real BAC and aren't captured by the simplified Widmark formula used here.

What counts as a 'standard drink'?

This calculator uses the common US definition of about 14 grams of pure alcohol — roughly a 355ml (12oz) beer, a 148ml (5oz) glass of wine, or a 44ml (1.5oz) shot of spirits.