Blood Alcohol Calculator
Predicts an average. Never predicts you.
Work out Blood Alcohol. Predicts an average. Never predicts you. States the assumption instead of hiding it.
Estimated BAC now
0.1348
Substantial impairment · above the stated limit
Widmark's formula divides the alcohol consumed by body mass times a distribution factor, then subtracts a linear elimination rate. The distribution factor differs between men and women mainly because of body water content, not body fat. Elimination is linear rather than exponential — roughly 0.015% an hour regardless of how much you drank, which is why nothing speeds it up. Coffee, cold showers and food after the fact make you a more alert drunk, not a soberer one. Food before drinking does matter, considerably. It slows absorption and lowers the peak, which is why the same drinks on an empty stomach produce a substantially higher blood alcohol than with a meal.
How the Blood Alcohol Calculator works
Estimated blood alcohol concentration by the Widmark formula, with time to zero and time under a limit you set. It is a way to understand how slowly alcohol clears — not a way to decide whether to drive.
Also known as: how long until i am sober · widmark formula calculator · bac from number of drinks · how long does alcohol stay in your system
Not medical advice. This calculator gives a general estimate, not medical advice. It cannot account for your individual health, medical history, or medication. Talk to a qualified healthcare professional before acting on any result.
Frequently asked questions
Can I use this to decide whether to drive?
No. Widmark's formula predicts a population average and individual results vary by 30% or more with food, hydration, medication and genetics. The only safe amount before driving is none.
How fast does alcohol leave the body?
Roughly 0.015% BAC an hour for most adults, and the elimination is linear rather than exponential — the rate barely depends on how much you drank.
Does coffee or a cold shower sober you up?
No. Nothing meaningfully speeds elimination. Caffeine and cold water make you a more alert drunk, which is arguably more dangerous than a sleepy one.
Does eating first make a difference?
A considerable one, but before rather than after. Food slows absorption and lowers the peak, so the same drinks on a full stomach produce a substantially lower blood alcohol.
Why does sex change the result?
The distribution factor differs mainly because of body water content, not body fat. Alcohol distributes into body water, so a smaller water compartment concentrates the same dose more.
Put this calculator on your own site
Free to use, on any site, commercial or not. Paste this where you want it to appear. It is a plain iframe, so it works in WordPress, Squarespace, Wix, Webflow, Ghost and anything else that accepts HTML.
<iframe src="https://www.thecalclibrary.com/embed/blood-alcohol-calculator" width="100%" height="640" style="border:1px solid #e2e8f0;border-radius:12px" loading="lazy" title="Blood Alcohol Calculator"></iframe>
<p style="font:13px/1.5 system-ui,sans-serif;margin:6px 0 0;color:#64748b">Powered by <a href="https://www.thecalclibrary.com/blood-alcohol-calculator" style="color:#64748b">Blood Alcohol Calculator</a> from The Calc Library</p>The only condition is that the credit line below the frame stays in place. That one line is what pays for the tool being free — it is how anyone else finds it.