BAC Calculator

Name: BAC Calculator
Author: Jitendra Kumar

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

Unit System

Sex Coefficient Profile

Widmark estimates use sex-specific body-water distribution coefficients.

Body Weight

Hours Since First Drink

BAC Elimination Rate

per hr

0.015 per hour is a common educational default. Real metabolism varies.

Extra Standard Drinks

drinks

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

Count

Serving Size

fl oz

ABV

Wine

Count

Serving Size

fl oz

ABV

Spirits

Count

Serving Size

fl oz

ABV

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.

Reviewed For Methodology, Labels, And Sources

Every CalculatorWallah calculator is published with visible update labeling, linked source references, and founder-led review of formula clarity on trust-sensitive topics. Use results as planning support, then verify institution-, policy-, or jurisdiction-specific rules where they apply.

Reviewed By

Jitendra Kumar, Founder & Editorial Standards Lead, oversees methodology standards and trust-sensitive publishing decisions.

Review editor profile

Topic Ownership

Sales tax and tax-sensitive estimate tools, Education and GPA planning calculators, Health, protein, and screening-formula pages, Platform-wide publishing standards and methodology

See ownership standards

Methodology & Updates

Page updated May 2026. Trust-critical pages are reviewed when official rates or rules change. Evergreen calculator guides are checked on a recurring quarterly or annual cycle depending on topic volatility.

Sources & methodology About the review process

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

BAC means blood alcohol concentration. In the United States, driving limits are commonly expressed as grams of alcohol per deciliter of blood, with 0.08 g/dL used by most states and 0.05 g/dL in Utah.

It uses a Widmark-style estimate from pure alcohol consumed, body weight, sex-based water distribution coefficient, elapsed time, and an assumed hourly elimination rate.

One U.S. standard drink contains about 0.6 fluid ounces, or 14 grams, of pure alcohol. That is roughly 12 oz beer at 5% ABV, 5 oz wine at 12% ABV, or 1.5 oz spirits at 40% ABV.

No. This is only an educational estimate and is not a legal, medical, breath, or blood test. Do not use it to decide whether to drive or do anything safety-critical.

Food, drink strength, serving size, drinking speed, body composition, medications, illness, sex, weight, absorption timing, and individual metabolism can all change actual BAC.

The default is 0.015 BAC per hour, a common educational assumption. Real elimination can be slower or faster, so changing this field should be treated as a sensitivity check, not a personal measurement.

Impairment starts below 0.08%, and laws can be stricter for commercial drivers, younger drivers, probation, workplace rules, and specific locations. A low estimate is not proof that driving is legal or safe.

Call emergency services if someone is unconscious, cannot be awakened, vomits repeatedly, breathes slowly or irregularly, has seizures, looks pale or bluish, or is confused and deteriorating.