Estimate blood alcohol after drinks
A Widmark estimate for 'how much is still in me' — and the honest caveat that no calculator can tell you it is safe to drive.
Tools used in this guide
The job
You drank, time passed, and you want a number. Widmark's formula estimates blood alcohol % from pure-alcohol grams, body weight, a sex-based distribution factor, and hours elapsed — the body clears roughly 0.015 % per hour.
What to enter
Pick a drink preset (beer, wine, shot) or set grams of pure alcohol directly — a 355 mL beer at 5 % is about 14 g. Enter weight, sex, and hours since you started; elimination counts from the start, not the last sip.
- Grams of pure alcohol = volume × ABV × 0.789.
- Adding more elapsed time lowers the estimate — but only time lowers it.
Worked example
Three 14 g beers over 2 h for a 70 kg male lands near 0.058 % — under the US 0.08 limit but above Japan's 0.03 % and most of Europe's 0.05 %. 'Legal somewhere' is not 'safe anywhere'.
Where it stops
r factors 0.68/0.55 are population averages; food, medications, and individual metabolism move the real number by a lot. This estimate explains a number — it is not a fitness-to-drive verdict, ever.