IMPORTANT WARNING: This calculator provides an estimate based on averages (Widmark Formula). It cannot account for individual metabolic rates, recent food consumption, medication, or genetic factors. NEVER use this calculator to determine if you are fit to drive. If you have been drinking, do not drive.
Understanding Alcohol Processing Rates
The human body metabolizes alcohol at a relatively constant rate, but the actual Blood Alcohol Concentration (BAC) reached depends heavily on several physiological variables. This Alcohol Processing Rate Calculator uses the Widmark Formula, the standard method for estimating BAC, to help you understand how long alcohol may remain in your system.
Key Factors Affecting Metabolism
While the average liver processes approximately 0.015 grams of alcohol per 100 milliliters of blood per hour (reducing BAC by 0.015% hourly), the peak level depends on:
Biological Sex: Men and women have different ratios of body water to fat. Men typically have a higher water content (approx. 68%) compared to women (approx. 55%), which dilutes alcohol more effectively.
Body Weight: A higher body weight provides a larger volume for the alcohol to be distributed, generally resulting in a lower peak BAC for the same amount of alcohol consumed.
Drink Strength (ABV) & Volume: The total mass of pure ethanol consumed is calculated by multiplying the volume of the drink by its Alcohol by Volume (ABV) percentage and the density of ethanol.
How the Calculation Works
This calculator determines your Estimated Peak BAC based on the total grams of alcohol consumed and your body metrics. It then subtracts the amount of alcohol your body has already metabolized over the time elapsed since you started drinking.
The "Zero" Limit: Even after you feel sober, your BAC may still be measurable. Professional drivers and those in safety-critical roles often require a 0.00% BAC, which can take significantly longer to achieve than simply dropping below the legal driving limit of 0.08%.
Standard Drink References
Beer: 12 oz at ~5% ABV
Wine: 5 oz at ~12% ABV
Distilled Spirits: 1.5 oz at ~40% ABV
function calculateProcessingRate() {
// 1. Get Inputs
var gender = document.getElementById('aprGender').value;
var weightLbs = parseFloat(document.getElementById('aprWeight').value);
var drinkCount = parseFloat(document.getElementById('aprDrinkCount').value);
var drinkVolOz = parseFloat(document.getElementById('aprDrinkVol').value);
var abv = parseFloat(document.getElementById('aprAbv').value);
var timeHours = parseFloat(document.getElementById('aprTime').value);
// 2. Validation
if (isNaN(weightLbs) || isNaN(drinkCount) || isNaN(drinkVolOz) || isNaN(abv) || isNaN(timeHours)) {
alert("Please fill in all fields with valid numbers.");
return;
}
if (weightLbs <= 0 || drinkVolOz <= 0 || abv < 0 || timeHours < 0) {
alert("Please enter positive values for weight, volume, and time.");
return;
}
// 3. Constants and Conversion
// Convert Weight to Grams (1 lb = 453.592 grams)
var weightGrams = weightLbs * 453.592;
// Widmark Constant (r) – Volume of distribution
// Men: 0.68, Women: 0.55
var r = (gender === 'male') ? 0.68 : 0.55;
// Density of Ethanol (0.789 g/ml)
var ethanolDensity = 0.789;
// Convert Drink Volume to ml (1 oz = 29.5735 ml)
var drinkVolMl = drinkVolOz * 29.5735;
// Metabolism Rate (Average beta) approx 0.015% per hour
var metabolismRate = 0.015;
// 4. Calculate Total Alcohol in Grams
// Formula: Count * Volume(ml) * (ABV/100) * Density
var totalAlcoholGrams = drinkCount * drinkVolMl * (abv / 100) * ethanolDensity;
// 5. Calculate Theoretical Max BAC (Before Metabolism)
// Widmark Formula: BAC = (Alcohol in Grams / (Body Weight in Grams * r)) * 100
var theoreticalMaxBAC = (totalAlcoholGrams / (weightGrams * r)) * 100;
// 6. Calculate Current BAC
// Current BAC = Max BAC – (Metabolism Rate * Time Elapsed)
var metabolizedBAC = metabolismRate * timeHours;
var currentBAC = theoreticalMaxBAC – metabolizedBAC;
// Handle negative BAC (if fully metabolized)
if (currentBAC 0) {
timeToZero = currentBAC / metabolismRate;
}
// 8. Calculate Time to 0.08% (Legal Limit in US/UK generally)
var timeToLimit = 0;
if (currentBAC > 0.08) {
timeToLimit = (currentBAC – 0.08) / metabolismRate;
}
// 9. Display Results
document.getElementById('resBAC').innerHTML = currentBAC.toFixed(4) + '%';
// Format time strings
var soberText = timeToZero <= 0 ? "You should be sober" : timeToZero.toFixed(1) + " hours";
var limitText = timeToLimit <= 0 ? "Below 0.08% limit" : timeToLimit.toFixed(1) + " hours";
document.getElementById('resSoberTime').innerHTML = soberText;
document.getElementById('resLimitTime').innerHTML = limitText;
// Show result box
document.getElementById('aprResult').style.display = 'block';
}