Blood Alcohol Content (BAC) Calculator

Calculate your estimated blood alcohol content (BAC) based on your gender, weight, alcohol consumption, and time elapsed. This calculator helps you understand how alcohol affects your body and provides information about potential impairment levels.

Disclaimer: This calculator provides estimates only and should not be used to determine whether you are legally able to drive or operate machinery. Many factors can affect BAC including medications, food consumption, and individual metabolism. Always err on the side of caution and never drink and drive. This calculator is for educational purposes only and is not intended to encourage alcohol consumption. If you have concerns about alcohol use, please consult a healthcare professional.

Gender

Weight

Drinks Consumed

Hours Since First Drink

Metabolism Rate Metabolism can be affected by age, medications, liver health, and other factors.

Stomach Content

Your Blood Alcohol Content Results

Estimated Blood Alcohol Content (BAC): 0.00%

Impairment Level: None

Time Until Sober: 0 hours

BAC Level	Typical Effects	Driving Impairment
0.00%	No alcohol in bloodstream	No impairment
0.01-0.03%	Slight mood changes	Minimal
0.04-0.06%	Feeling of relaxation, minor impairment	Declining alertness
0.07-0.09%	Mild impairment of balance, speech, vision	Reduced coordination (0.08% is legally impaired in most states)
0.10-0.12%	Significant impairment of coordination and judgment	Reduced ability to track moving objects
0.13-0.15%	Blurred vision, major loss of balance	Substantial impairment in vehicle control
0.16-0.20%	Dysphoria, nausea, possible vomiting	Severe impairment in all driving skills
0.21-0.29%	Severe motor impairment, blackouts, loss of consciousness	Cannot drive safely
0.30-0.39%	Life-threatening, loss of consciousness	Cannot drive
0.40%+	Onset of coma, possible death due to respiratory arrest	Cannot drive

Understanding Your BAC Results

BAC (Blood Alcohol Content): The percentage of alcohol in your bloodstream.
Legal Limit: In most U.S. states, the legal BAC limit for driving is 0.08%. Some countries have lower limits (0.05% or even 0.02%).
Metabolism: On average, the body metabolizes alcohol at a rate of about 0.015% per hour, though this varies by individual.
Impairment: Impairment begins with the first drink, well before reaching the legal limit.

Important: This calculator provides estimates only. Actual BAC can vary based on many factors not accounted for in this calculation. Never rely on this calculator to determine if you are fit to drive. If you've been drinking, use alternative transportation.

How the BAC Calculator Works

This calculator uses the Widmark formula, a widely accepted method for estimating blood alcohol content:

The Widmark Formula

BAC = (A × 5.14 / (W × r)) - (0.015 × H)

Where:

BAC = Blood Alcohol Content (percentage)
A = Total alcohol consumed (in ounces of pure alcohol)
W = Body weight (in pounds)
r = Gender constant (0.68 for men and 0.55 for women)
H = Hours since first drink
0.015 = Average hourly elimination rate of alcohol from the bloodstream

Calculating Alcohol Content in Drinks

The amount of pure alcohol in a drink is calculated as:

Pure Alcohol (oz) = Volume of drink (oz) × (Alcohol percentage / 100)

Standard drink equivalents:

12 oz beer (5% alcohol) = 0.6 oz pure alcohol
5 oz wine (12% alcohol) = 0.6 oz pure alcohol
1.5 oz liquor/spirits (40% alcohol) = 0.6 oz pure alcohol

Adjustments for Metabolism and Food

The calculator makes additional adjustments based on:

Metabolism Rate: Slow (-15%), Normal (no adjustment), Fast (+15%)
Stomach Content: Empty Stomach (+20%), Some Food (no adjustment), Full Meal (-20%)

Time Until Sober

The estimated time until sobriety is calculated as:

Time Until Sober (hours) = Current BAC / 0.015

This assumes the average elimination rate of 0.015% BAC per hour, adjusted for the selected metabolism rate.

It's important to note that many factors can affect BAC and alcohol metabolism that aren't accounted for in this calculation, including age, liver function, medications, fatigue, and overall health. This calculator provides estimates only and should not be used to determine whether you are fit to drive or operate machinery.