BAC Calculator
Estimate blood alcohol content from drinks, body weight, sex coefficient profile, elapsed time, and metabolism assumptions.
Last Updated: May 2026
Do Not Use This to Decide Whether to Drive
This is an educational estimate, not a breathalyzer, blood test, legal opinion, or safety clearance. If alcohol is involved, choose a sober ride.
Alcohol Estimate
Estimate BAC from drinks, body weight, and time
Enter drink counts, serving sizes, ABV, elapsed time, and a metabolism assumption to estimate current BAC and time-to-threshold values.
Person and Time Inputs
Widmark estimates use sex-specific body-water distribution coefficients.
0.015 per hour is a common educational default. Real metabolism varies.
Use this for drinks that do not fit the beer, wine, or spirits rows.
Drink Inputs
Drink sizes use U.S. fluid ounces because U.S. standard drink definitions are based on fluid ounces of pure alcohol.
Beer, Cider, Seltzer
Wine
Spirits
BAC Calculator Disclaimer
This calculator is an educational estimate only. It is not a breathalyzer, blood test, legal measurement, medical diagnosis, or safety clearance. Do not use it to decide whether to drive, operate equipment, swim, supervise others, or make any safety-critical decision. If someone may have alcohol poisoning, call emergency services immediately.
Professional Review Status
This YMYL page has internal methodology review, but no external credentialed professional review is recorded yet.
- Reliance status
- Credentialed health review required before medical reliance
- Required credentials
- licensed physician, registered dietitian, qualified clinician
- Review scope
- screening limitations, nutrition or body-composition assumptions, safety warnings, contraindication language, and medical disclaimer placement
Current reviewer: Iliyas Khan, Internal healthcare operations and claims-context reviewer (HIPAA Compliance Certified).
This page is for general education and planning. It is not medical diagnosis, treatment, nutrition therapy, or a substitute for care from a qualified clinician.
Health credentialed review: professional reliance limit
This page is for general education and planning. It is not medical diagnosis, treatment, nutrition therapy, or a substitute for care from a qualified clinician. Results should be treated as a preliminary estimate, not a filing instruction, diagnosis, product recommendation, eligibility decision, or compliance sign-off. Required professional review: licensed physician, registered dietitian, qualified clinician. Source expectation: Review should cite public-health, academic, medical, or recognized clinical sources for formulas and safety thresholds.
Checked by Iliyas Khan
BAC Calculator is checked for formula labels, source links, and result limits.
Iliyas Khan, Chief Operating Officer. Updated May 2026. Scope: health calculators.
Health credentialed review: Named internal reviewer: Iliyas Khan, Chief Operating Officer. External credentialed professional review is still required before this page is treated as professional advice.
Internal healthcare operations and claims-context reviewer. Review scope: non-clinical healthcare operations context, insurance/claims language, calculator limitations, and escalation warnings.
Credentials on file: HIPAA Compliance Certified.
Relevant review context: Medical Billing Subject Matter Expert with 5+ years of hands-on RCM experience; Medical billing and coding experience: CPT, ICD-10, and HCPCS; Healthcare revenue cycle management, claims, denial management, and compliance workflow experience.
Required professional credentials: licensed physician, registered dietitian, qualified clinician. Scope: screening limitations, nutrition or body-composition assumptions, safety warnings, contraindication language, and medical disclaimer placement.
This page is for general education and planning. It is not medical diagnosis, treatment, nutrition therapy, or a substitute for care from a qualified clinician.
How to Use This Calculator
Step 1: Enter body details
Choose pounds or kilograms, select the sex coefficient profile, and enter body weight.
Step 2: Enter drinking timeline
Add hours since the first drink and the BAC elimination rate assumption.
Step 3: Add drinks
Enter beer, wine, spirits, and any extra standard-drink equivalents.
Step 4: Estimate BAC
Review current BAC, peak BAC, standard drinks, pure alcohol, and timing estimates.
Step 5: Use the warning context
Treat the result as an educational estimate only, never as legal or safety clearance.
How This Calculator Works
The calculator first converts each drink into fluid ounces of pure alcohol using serving size and alcohol by volume. It then converts total pure alcohol into U.S. standard drinks using 0.6 fluid ounces per standard drink.
The BAC estimate uses a Widmark-style formula with body weight, a sex-based body-water distribution coefficient, and elapsed time. The default elimination rate is 0.015 BAC per hour, but real metabolism varies by person and situation.
BAC estimates are sensitive to drink strength, serving size, drinking speed, food, medications, illness, and absorption timing. Treat every output as approximate and unsuitable for legal or safety decisions.
What You Need to Know
1) BAC Formula Used
This tool uses a practical Widmark-style estimate. It is useful for education and comparing assumptions, but it does not measure actual blood alcohol concentration.
| Step | Formula | Purpose |
|---|---|---|
| Pure alcohol | Drink count x serving size x ABV | Converts each drink row into fluid ounces of pure alcohol. |
| Standard drinks | Pure alcohol fl oz / 0.6 | Uses the U.S. standard drink definition of about 0.6 fl oz pure alcohol. |
| Peak BAC | (Pure alcohol oz x 5.14) / (body weight lb x Widmark ratio) | Uses a male ratio of 0.73 and female ratio of 0.66. |
| Current BAC | Peak BAC - (elapsed hours x elimination rate) | Floors at zero and defaults to 0.015 BAC per hour. |
2) Standard Drinks Matter
A standard drink depends on pure alcohol, not only the size of the glass. The NIAAA and CDC describe one U.S. standard drink as about 14 grams, or 0.6 fluid ounces, of pure alcohol. That is roughly a 12 oz beer at 5% ABV, 5 oz wine at 12% ABV, or 1.5 oz spirits at 40% ABV.
3) Interpreting BAC Levels
NHTSA notes that impairment begins before the common 0.08 g/dL limit. The table below summarizes practical thresholds used on this page.
| Estimated BAC | Typical concern | Safety note |
|---|---|---|
| 0.02% | Some loss of judgment can begin | Driving skills can be affected even at low BAC levels. |
| 0.05% | Coordination and alertness can decline | Utah uses 0.05 g/dL as the general per se driving limit. |
| 0.08% | Clear impairment in reaction time, perception, and judgment | Most U.S. states use 0.08 g/dL as the general per se limit. |
| 0.15% | Severe impairment risk | Balance, control, vomiting, and poisoning risk become major concerns. |
4) Legal and Safety Limits
NHTSA and CDC state that most U.S. states use 0.08 g/dL as the general per se driving limit, while Utah uses 0.05 g/dL. Stricter rules can apply for commercial drivers, younger drivers, probation, employment, boating, and local regulations.
The safest interpretation is simple: a calculator result should never be used to decide whether driving is legal or safe. If alcohol is involved, use a sober driver, rideshare, taxi, transit, or stay put.
5) Where to Go Next
For broader wellness planning, compare this estimate with the Calorie Calculator, Sleep Calculator, and Target Heart Rate Calculator.
Keep the research moving with Calorie Calculator, Sleep Calculator, Target Heart Rate Calculator, and BMI Calculator.
Frequently Asked Questions
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Sources & References
- 1.NHTSA - Drunk Driving(Accessed May 2026)
- 2.CDC - Impaired Driving(Accessed May 2026)
- 3.NIAAA - What Is A Standard Drink?(Accessed May 2026)
- 4.CDC - About Standard Drink Sizes(Accessed May 2026)