BAC Calculator: Estimate Blood Alcohol and Time Back to Zero
Want a rough idea of your blood alcohol and how long it takes to clear? This uses the classic Widmark formula and the average elimination rate of about 0.015% per hour. It's an estimate, so if you've been drinking, don't drive, full stop.
Ad: we may earn a commission if you buy through this link. Information only, not medical or legal advice. Tampering with a drug test can be illegal and usually counts as a refusal. The only sure way to pass is to not use.
The math, in plain English
Widmark's formula: BAC = (alcohol in ounces x 5.14) / (body weight in lb x r) - 0.015 x hours. A US standard drink holds about 0.6 oz (14 g) of pure alcohol. "r" is the share of your body that's water, around 0.73 for men and 0.66 for women on average.
Ad: we may earn a commission if you buy through this link. Information only, not medical or legal advice. Tampering with a drug test can be illegal and usually counts as a refusal. The only sure way to pass is to not use.
What 0.08% means
0.08% is the legal per se limit for most adult drivers in the US (Utah uses 0.05%). Commercial drivers face 0.04%, and under-21 drivers face zero-tolerance limits. Impairment starts well below those numbers.
Check yourself
A fuel-cell breathalyzer gives a far better reading than any calculator. Even then, use it for your own information, never as a green light to drive.
Questions people ask
How fast does the body clear alcohol?
On average about 0.015% BAC per hour, roughly one standard drink an hour. Coffee, cold showers and water don't speed it up.
Is this accurate enough for court or work?
No. It's an educational estimate only.
Ad: we may earn a commission if you buy through this link. Information only, not medical or legal advice. Tampering with a drug test can be illegal and usually counts as a refusal. The only sure way to pass is to not use.
No product can promise you a pass, and the only certain way is to not use. Tampering with a drug test can be illegal and is usually treated as a refusal. We never help anyone beat DOT, federal, safety-sensitive, or court-ordered tests. If substance use is getting on top of you, call the free, confidential SAMHSA National Helpline on 1-800-662-4357 (24/7, English and Spanish), or call or text 988 in a crisis. Source: samhsa.gov.