Blood Alcohol Concentration Calculator
Never use this estimate to decide whether to drive
If you have been drinking, do not drive, cycle, ride a scooter, or operate machinery regardless of the result. Arrange a sober ride.
This is a simplified Widmark estimate. Actual BAC can differ widely with absorption, food, body composition, liver function, medication, drinking pace, and individual variation. Only breath or blood testing measures BAC.
The operator is not responsible for driving, medical, or legal decisions made using this calculator, or for any resulting consequences.
Body weight and elapsed time
The distribution profile selects an average body-water factor for the equation. It does not precisely represent gender identity or an individual's body composition.
Uses a typical male factor of 0.68 or typical female factor of 0.55.
Count from when drinking began, not from the final drink.
Alcohol consumed
Prefer the labeled or measured volume and ABV. For a mixed drink, entering each alcoholic ingredient separately gives a more consistent estimate.
Drink entry #1
Reference BAC estimate
Current estimated range
Low estimated range
Even a small amount can change attention and judgment. Do not interpret this as a safe driving range.
Estimated current BAC
0.006%
Simplified estimate at the entered elapsed time
BAC assuming full absorption
0.036%
Value before subtracting time-based elimination
Pure alcohol
19.7 g
Volume × ABV × ethanol density × servings
Standard drink equivalents
1.41
Based on the NIAAA definition of 14g pure alcohol
Until model reaches zero
25m
This is not a safe-to-drive time
Applied elimination rate
0.015%/hr
Average reference of 0.015% BAC per hour
Simplified decline from now
Now
0.006%
+1h
0.000%
+2h
0.000%
+3h
0.000%
+4h
0.000%
+6h
0.000%
Your body is not guaranteed to eliminate alcohol at this constant rate. Coffee, cold showers, and exercise do not rapidly lower BAC.
How it is calculated
The simplified Widmark model divides grams of pure alcohol by body weight and a distribution factor, then subtracts 0.015% BAC per hour since drinking began. It assumes instantaneous absorption.
Why can the real value differ?
Food, drinking pace, stomach emptying, body water, medication, and health can change both the peak and decline. BAC can keep rising after drinking stops because alcohol in the stomach and intestine continues to enter the blood.
Alcohol overdose warning signs
If someone cannot be awakened, is confused, repeatedly vomits, has a seizure, breathes slowly or irregularly, or has pale or bluish skin, stop calculating and call local emergency services immediately. Do not leave them alone.
Limits of Estimated Blood Alcohol Concentration
Reference date and last reviewed: July 11, 2026
Calculation Basis
It estimates pure alcohol from the entered drinks and applies a simple body-weight, distribution-factor, and elapsed-time model for reference.
Reference Limits
It does not model delayed absorption, food, body composition, individual metabolism, medication, measurement error, or local legal limits, and it cannot determine real BAC or fitness to drive.
When to Confirm Officially
Do not drive or perform dangerous work after drinking. If someone is unresponsive, repeatedly vomiting, seizing, or breathing slowly, contact emergency services without waiting for the estimate.
Usage Tips
Check the labeled volume and ABV instead of counting glasses alone
Beer, wine, soju, and mixed drinks can contain very different amounts of pure alcohol even when they look like one serving. Enter the labeled volume and ABV together with time since the first drink for a more consistent comparison. The estimate is not a breath or blood test and must never be used to decide whether to drive.
What is Blood Alcohol Concentration Calculator?
The Blood Alcohol Concentration Calculator uses body weight, a Widmark distribution profile, time since drinking began, and each drink's volume, ABV, and servings to estimate pure alcohol and BAC. It applies a simplified Widmark model that divides grams of alcohol by body weight and an average distribution factor, then subtracts 0.015% BAC per hour. The model assumes instantaneous absorption and a constant elimination rate, so it cannot reproduce an individual's actual absorption and metabolism. The result is not a breath or blood test, medical evaluation, legal evidence, or permission to drive.
How to Use
- 1Choose the typical male or typical female Widmark distribution profile. This changes only the average calculation factor and does not measure body composition.
- 2Enter body weight and select kilograms or pounds.
- 3Enter time elapsed since the first drink began.
- 4For every drink, enter the measured volume in milliliters, ABV, and servings. Prefer the product label and list alcoholic ingredients of mixed drinks separately.
- 5Review pure alcohol, 14g standard drink equivalents, BAC assuming full absorption, estimated current BAC, and the time-based decline scenario.
- 6Do not use a low or zero result to decide whether to drive. Arrange a sober ride after drinking.
Separate alcohol mass from the BAC model
Last reviewed: July 11, 2026Simplified BAC calculation
pure alcohol(g) = volume(mL) × ABV ÷ 100 × 0.789 × servings; estimated BAC = max(0, (alcohol g ÷ (weight kg × distribution factor) ÷ 10) − 0.015 × elapsed hours)
The tool first estimates ethanol mass, then applies a simple Widmark distribution and hourly elimination assumption for reference only.
A 70kg man drinks two 500mL beers
- • 70kg with the male distribution factor 0.68
- • Two 500mL beers at 5% ABV
- • Two hours since the first drink
- 1. Alcohol = 500 × 0.05 × 0.789 × 2 = 39.45g
- 2. Peak BAC is about 0.0829%; after two hours the model gives 0.0529%
The estimate is about 39.5g of pure alcohol, a modeled current BAC of 0.0529%, and about 2.82 standard drinks.
How to read the result
- Volume, ABV, and serving count matter more than the drink label when estimating pure alcohol.
- Elapsed time changes the simple model but cannot represent delayed absorption or personal metabolism.
Conditions that change the result
- Real BAC varies with absorption, food, body composition, liver function, medication, and individual differences.
- The estimate is not a breath test, blood test, legal driving decision, or medical measurement.
Common input mistakes
- Counting glasses without entering their volume and ABV hides large differences between drinks.
- A low-looking number should never be used as permission to drive or operate dangerous equipment.
Reference Knowledge
- ●Pure alcohol is calculated as beverage volume in mL × ABV ÷ 100 × ethanol density of 0.789g/mL × servings.
- ●The U.S. National Institute on Alcohol Abuse and Alcoholism defines one U.S. standard drink as about 14g of pure alcohol. Standard drink definitions vary by country: https://www.niaaa.nih.gov/alcohols-effects-health/what-standard-drink
- ●This simplified Widmark calculation uses distribution factors of 0.68 for the typical male profile and 0.55 for the typical female profile, then subtracts 0.015% BAC per hour since drinking began. Both factors vary substantially between people and occasions.
- ●The U.S. National Highway Traffic Safety Administration explains that even small amounts of alcohol can affect driving and that it is very difficult to assess your own BAC or impairment: https://www.nhtsa.gov/risky-driving/drunk-driving
- ●NHTSA's effects table describes changes in visual function and divided attention around 0.02% BAC, with increasing impairment of judgment, coordination, reaction, and memory at higher concentrations. Individual response and legal limits vary.
- ●NIAAA warns that BAC can continue rising after drinking stops or a person becomes unconscious because alcohol in the stomach and intestine continues to enter the bloodstream: https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/understanding-dangers-of-alcohol-overdose
- ●Inability to wake, repeated vomiting, seizures, slow or irregular breathing, and pale or bluish skin are emergency signs of alcohol overdose. Call local emergency services immediately instead of waiting for a calculation.
FAQ
Q.Can I drive if the calculator displays 0.000%?
No. It only means the simplified equation reached zero. It does not prove that measured BAC is zero or that driving ability has recovered. Absorption, elimination, and input uncertainty are too variable to use this calculator for driving decisions.
Q.When does elapsed time begin?
Count from when the first drink began. The calculator does not model the exact time of each serving or delayed absorption; it simplifies all entered alcohol as if it were absorbed immediately.
Q.Why do the male and female profiles produce different estimates?
Traditional Widmark equations use different average distribution factors to represent population differences in body water. Real body water and body composition vary widely within each sex, so the profile is an average assumption rather than a personal measurement.
Q.Can coffee, water, exercise, or a cold shower lower BAC quickly?
No. They may change how awake someone feels but do not rapidly remove alcohol from the blood. Metabolism takes time. Reduced consciousness or abnormal breathing requires immediate emergency help.
Q.Can I compare this estimate with a legal driving limit?
Legal limits vary by country, region, driver type, and age, and a person can be impaired or penalized below a stated threshold. This calculator is not a legal test or measuring device, and no displayed value should be treated as permission to drive.
