BAC Calculator: Estimate Blood Alcohol Concentration
Estimate current BAC from drink count, body weight, biological sex, and elapsed time. Use it for alcohol metabolism context, not as a legal, driving, medical, or safety decision.
Editorial note
This educational page is maintained by EtGCalc and reviewed against published EtG research, SAMHSA guidance, and our calculator methodology. It does not provide medical or legal advice.
BAC Calculator
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Current preset: Beer, 12 oz / 5%. Use custom ABV only when your serving differs.
BAC estimates current blood alcohol; EtG estimates a longer urine detection window.
How this BAC calculator works
The calculator uses standard drink math and the Widmark equation, then subtracts an average alcohol metabolism rate. NIAAA defines a U.S. standard drink as about 14 grams of pure alcohol, such as 12 oz beer at 5%, 5 oz wine at 12%, or 1.5 oz spirits at 40%.
Breath alcohol tool
If your question is current breath alcohol, a calibrated breathalyzer is closer to the question than an EtG urine strip. No device or calculator can guarantee safety.
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Do not use this as clearance advice
A BAC estimate can be wrong in either direction. Do not use this tool to decide whether to drive, operate equipment, work, take a test, or make a legal decision.
Official references
BAC vs EtG: which calculator should you use?
BAC and EtG answer different alcohol-testing questions. BAC is about current alcohol; EtG is about a longer urine detection window after alcohol has been metabolized.
| Question | BAC | EtG |
|---|---|---|
| What it measures | Alcohol currently in blood or breath | Ethyl glucuronide metabolite in urine |
| Typical question | What is my current alcohol level? | Could recent alcohol use still be detectable? |
| Common tool | Breathalyzer or blood test | Urine EtG strip, dip card, or lab test |
| Best site tool | BAC Calculator | EtG urine test calculator |
Why the same drinks can produce different BAC
Two people can drink the same number of standard drinks and have different BAC estimates. Body water, sex, body weight, drinking speed, food, and timing all change the estimate.
NHTSA explains that BAC can be measured with a breathalyzer or a blood test, and that even low BAC levels can affect driving ability. This page is for learning how the math works, not for deciding whether an activity is safe.
Frequently Asked Questions
What does a BAC calculator estimate?
A BAC calculator estimates blood alcohol concentration from inputs such as standard drinks, body weight, biological sex, and elapsed time. It is an educational estimate, not a measured breath or blood result.
Is BAC the same as EtG?
No. BAC estimates current alcohol in blood or breath. EtG is a urine alcohol metabolite marker that can remain detectable after breath alcohol has returned to zero.
How fast does BAC go down?
Many educational calculators use an average metabolism rate near 0.015 percentage points per hour, but real metabolism varies. Food, drinking pattern, health, medications, and individual biology can change the result.
Can this calculator tell me if I am safe to drive?
No. Do not use an online calculator to decide whether driving, work, or any safety-sensitive activity is safe or legal. Only a calibrated testing device or lab method can measure actual alcohol level.
Related Reading
How Long Alcohol Stays on Breath
Breath alcohol timing, breathalyzers, and current BAC context.
EtG vs BAC
Understand current alcohol testing vs longer-window urine biomarkers.
EtG Urine Test Calculator
Use this when your question is urine EtG cutoffs and detection windows.
Alcohol Test Strips Guide
Compare EtG strips, dip cards, saliva strips, and breath tools.
Medical & Legal Disclaimer
Not Medical Advice
EtGCalc does not provide diagnosis, treatment, or medical advice. Talk with a qualified healthcare provider about alcohol use, metabolism, testing concerns, or recovery.
Not Legal Advice
EtG testing can affect probation, custody, licensing, and employment decisions. Consult a licensed attorney or your testing program for legal questions.
If You Need Support
In the United States, SAMHSA's National Helpline is 1-800-662-4357. It is free, confidential, and available 24/7.
Calculator output is an estimate, not a test prediction. Individual metabolism, hydration, kidney function, genetics, specimen handling, and lab cutoff policy can change real results. See our methodology and sources.