BAC Estimator
Estimate blood alcohol concentration from drinks, weight, and time — an estimate, not a test.
Quick answer: enter your details below and click Estimate BAC — your result appears instantly, right here in your browser. Nothing you enter is uploaded or stored.
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Enter your details below.
How to use
- Enter how many standard drinks you had.
- Enter your body weight and select the formula set.
- Enter the hours since your first drink.
- Click Estimate BAC.
About this tool
This estimator uses the Widmark formula as a rough guide: it spreads the alcohol across body water by sex, then subtracts a steady elimination rate over time. It is an estimate only and never a reason to drive — the only safe choice after drinking is not to drive. This tool is not medical advice; if you feel unwell after drinking, seek help.
Frequently asked questions
What is a standard drink here?
One standard drink is counted as 14 g of pure alcohol, the US convention used by this formula.
Why does sex change the result?
The formula uses a different body-water factor for men and women, which changes how the same alcohol spreads.