Estimate Blood Alcohol Content from drinks consumed, body weight and time elapsed — with sober-by time and legal limit guidance. For educational use only.
Enter your figures and click Calculate to see your results.
Enter your gender, body weight and unit, the number of standard drinks consumed and how many hours have passed since your first drink.
Press the Calculate button. Results appear instantly using standard clinical and scientific formulas.
Results are displayed with all key values clearly labelled. Use the Copy button to grab your results or Download to save a text file. For health decisions, always consult a healthcare professional.
This tool uses the Widmark formula: BAC = (grams of alcohol / (body weight in grams × r)) − (0.015 × hours elapsed), where r = 0.68 for men and 0.55 for women. One standard US drink ≈ 14g of pure alcohol. The result is an estimate — individual metabolism varies significantly.
The liver metabolises alcohol at roughly 0.015% BAC per hour — approximately one standard drink per hour. Nothing speeds this up: not coffee, food, cold water or exercise. Only time eliminates alcohol from your bloodstream. Water helps prevent dehydration but does not reduce BAC.
A US standard drink = 14g pure alcohol: 355ml regular beer (5%), 148ml wine (12%), or 44ml spirits (40%). Standard drink definitions differ by country: UK = 8g, Australia = 10g, Japan = 20g. Always check the actual alcohol content of what you are drinking.
In most US states, the legal limit is 0.08% BAC. In the UK, England/Wales limit is 80mg per 100ml blood (0.08%), Scotland 50mg (0.05%). In many European countries it is 0.05% or lower. Some countries have zero tolerance. Never drive if you have consumed alcohol — even below the legal limit, impairment begins immediately.
This provides an estimate only. Actual BAC varies significantly based on individual metabolism, liver health, medications, food intake and other factors. Never rely on a calculated BAC to decide whether it is safe to drive. The only accurate measurement is a certified breathalyser or blood test.
