function calculateBAC() {
var numDrinks = parseFloat(document.getElementById('numDrinks').value);
var drinkAlcoholOz = parseFloat(document.getElementById('drinkAlcoholOz').value);
var bodyWeightLbs = parseFloat(document.getElementById('bodyWeightLbs').value);
var genderMale = document.getElementById('genderMale').checked;
var timeElapsedHours = parseFloat(document.getElementById('timeElapsedHours').value);
if (isNaN(numDrinks) || numDrinks < 0) {
alert("Please enter a valid number of drinks.");
return;
}
if (isNaN(drinkAlcoholOz) || drinkAlcoholOz <= 0) {
alert("Please enter a valid amount of pure alcohol per drink.");
return;
}
if (isNaN(bodyWeightLbs) || bodyWeightLbs <= 0) {
alert("Please enter a valid body weight.");
return;
}
if (isNaN(timeElapsedHours) || timeElapsedHours < 0) {
alert("Please enter a valid time elapsed.");
return;
}
// Constants for Widmark Formula
var alcoholGramsPerOz = 28.35; // grams per ounce
var bodyWeightGramsPerLb = 453.592; // grams per pound
var distributionRatio; // r value
if (genderMale) {
distributionRatio = 0.68; // Men
} else {
distributionRatio = 0.55; // Women
}
var metabolismRatePerHour = 0.015; // Average BAC reduction per hour (%)
// Calculate total alcohol consumed in grams
var totalAlcoholGrams = numDrinks * drinkAlcoholOz * alcoholGramsPerOz;
// Calculate body weight in grams
var bodyWeightGrams = bodyWeightLbs * bodyWeightGramsPerLb;
// Calculate initial BAC using Widmark Formula
// BAC = [Alcohol_consumed_grams / (Body_weight_grams * r)] * 100
var initialBAC = (totalAlcoholGrams / (bodyWeightGrams * distributionRatio)) * 100;
// Account for metabolism over time
var metabolizedAlcohol = timeElapsedHours * metabolismRatePerHour;
var finalBAC = initialBAC – metabolizedAlcohol;
// Ensure BAC doesn't go below zero
if (finalBAC = 0.40) {
interpretation = "Extremely high risk of coma or death. Seek immediate medical attention.";
} else if (finalBAC >= 0.30) {
interpretation = "Severe intoxication, potential for blackout, loss of consciousness.";
} else if (finalBAC >= 0.20) {
interpretation = "Major motor impairment, vomiting, potential for 'blackout'.";
} else if (finalBAC >= 0.15) {
interpretation = "Significant impairment of motor control, slurred speech, blurred vision.";
} else if (finalBAC >= 0.08) {
interpretation = "Legally intoxicated in most U.S. states. Impaired judgment, coordination, and driving ability.";
} else if (finalBAC >= 0.05) {
interpretation = "Reduced coordination, impaired judgment, exaggerated behavior.";
} else if (finalBAC >= 0.02) {
interpretation = "Slight mood alteration, relaxation, minor impairment of judgment.";
} else {
interpretation = "Little to no alcohol effect. Always drink responsibly.";
}
document.getElementById('bacInterpretation').innerText = interpretation;
}
Understanding Your Blood Ethanol Content (BAC)
Blood Ethanol Content, commonly known as Blood Alcohol Content (BAC), is a measure of the amount of alcohol in your blood, expressed as a percentage. It's a critical metric for understanding the level of intoxication and its potential effects on your body and mind. This calculator provides an estimate of your BAC based on several key factors.
How BAC is Calculated
The calculation of BAC is complex, but generally relies on a formula known as the Widmark Formula, which considers the total amount of alcohol consumed, your body weight, and your gender. The body metabolizes alcohol over time, so the duration since your first drink also plays a significant role.
Alcohol Consumed: The more alcohol you drink, the higher your BAC will be. This is measured by the number of standard drinks and the pure alcohol content per drink.
Body Weight: Generally, a heavier person will have a lower BAC than a lighter person who consumes the same amount of alcohol, because alcohol is distributed throughout the body's water content.
Gender: Women typically achieve higher BACs than men after consuming the same amount of alcohol. This is due to several factors, including generally lower body water content and differences in alcohol-metabolizing enzymes.
Time Elapsed: Your liver metabolizes alcohol at a relatively constant rate (approximately 0.015% per hour for most people). The longer the time since your first drink, the more alcohol your body has processed, leading to a lower BAC.
Food Consumption: While not directly factored into this calculator, eating before or during drinking can slow the absorption of alcohol into the bloodstream, but it does not prevent it from being absorbed entirely.
What is a "Standard Drink"?
In the United States, a "standard drink" contains approximately 0.6 fluid ounces (14 grams) of pure alcohol. This amount is typically found in:
12 ounces of regular beer (about 5% alcohol)
5 ounces of wine (about 12% alcohol)
1.5 ounces of distilled spirits (about 40% alcohol, or 80 proof)
It's important to note that many alcoholic beverages, especially craft beers, large wine pours, or mixed drinks, often contain significantly more than one standard drink.
BAC Levels and Their Effects
The effects of alcohol vary greatly among individuals, but general guidelines for BAC levels include:
0.02% – 0.03%: Slight mood elevation, relaxation, minor impairment of judgment.
0.08%: Legally intoxicated in most U.S. states. Significant impairment of muscle coordination, judgment, self-control, reasoning, and memory. Driving is extremely dangerous.
0.10% – 0.12%: Slurred speech, poor balance, slower reaction time, clear impairment of motor control.
0.15% – 0.20%: Major loss of balance and motor control, vomiting, significant impairment of mental faculties.
0.25% – 0.30%: Severe intoxication, potential for blackout, loss of consciousness, increased risk of choking on vomit.
0.35% – 0.40%+: Life-threatening. Coma, respiratory arrest, and potential for death.
Important Disclaimer
This Blood Ethanol Content calculator provides an estimate for informational purposes only and should not be used as a definitive measure of intoxication or for legal purposes. Individual responses to alcohol can vary widely due to factors like medication, health conditions, fatigue, and tolerance. Always drink responsibly, never drink and drive, and consult a medical professional for health-related concerns.