Calculate Bac Level

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BAC Level Calculator

Estimate Your Blood Alcohol Content

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Estimated BAC Level:

Understanding Your BAC Level

Blood Alcohol Content (BAC) is a measurement used to determine the amount of alcohol present in a person's bloodstream. It is expressed as a percentage. For example, a BAC of 0.08% means that there are 0.08 grams of alcohol for every 100 milliliters of blood.

How BAC is Calculated (The Widmark Formula)

This calculator utilizes the Widmark Formula, which is the gold standard for forensic alcohol estimation. The calculation takes into account your weight, gender (which affects water distribution in the body), the total volume of alcohol consumed, and the elapsed time since you started drinking.

The Formula:
BAC = [ (Alcohol Consumed in grams / (Body Weight in grams × r)) × 100 ] – (Time in hours × 0.015)
  • r: Gender constant (0.68 for men, 0.55 for women)
  • 0.015: The average rate at which the body metabolizes alcohol per hour.

BAC Effects and Legal Limits

BAC Range Typical Effects
0.02% – 0.03% Mild relaxation, slight mood elevation.
0.05% – 0.06% Reduced inhibitions, minor impairment of reasoning and memory.
0.08% Legal limit for driving in most of the US. Impaired balance, speech, and reaction time.
0.10% – 0.12% Significant motor impairment and loss of judgment.
0.20% + Severe intoxication, potential blackout, nausea/vomiting.

Realistic Examples

Example 1: A 180 lb male who drinks three 12oz beers (5% ABV) over 2 hours. His estimated BAC would be approximately 0.034%, which is below the legal driving limit.

Example 2: A 130 lb female who drinks two 5oz glasses of wine (12% ABV) in 1 hour. Her estimated BAC would be approximately 0.062%, approaching the legal limit.

IMPORTANT DISCLAIMER: This calculator provides an estimate only. Many factors including food intake, medication, hydration levels, and metabolic rate can significantly alter your actual BAC. Never use this tool to determine if it is safe or legal for you to drive. If you have been drinking, do not drive.
function calculateBAC() { var r = parseFloat(document.getElementById('bac_gender').value); var weightLbs = parseFloat(document.getElementById('bac_weight').value); var drinks = parseFloat(document.getElementById('bac_drinks').value); var abv = parseFloat(document.getElementById('bac_abv').value); var size = parseFloat(document.getElementById('bac_size').value); var time = parseFloat(document.getElementById('bac_time').value); var resultBox = document.getElementById('bac_result_box'); var finalValue = document.getElementById('bac_final_value'); var statusText = document.getElementById('bac_status'); var warningText = document.getElementById('bac_warning'); if (isNaN(weightLbs) || isNaN(drinks) || isNaN(abv) || isNaN(size) || isNaN(time) || weightLbs <= 0) { alert("Please enter valid positive numbers for all fields."); return; } // Convert weight to grams (1 lb = 453.592 grams) var weightGrams = weightLbs * 453.592; // Total oz of alcohol var totalOzAlcohol = drinks * size * (abv / 100); // Convert oz of alcohol to grams (1 fl oz of alcohol is approx 23.36 grams) // Formula: Oz * 29.5735 (ml/oz) * 0.789 (density of ethanol) var gramsAlcohol = totalOzAlcohol * 29.5735 * 0.789; // Widmark Formula // BAC = [ (Alcohol in grams / (Weight in grams * r)) * 100 ] – (Time * 0.015) var rawBAC = ((gramsAlcohol / (weightGrams * r)) * 100) – (time * 0.015); // BAC cannot be negative if (rawBAC = 0.08) { resultBox.style.backgroundColor = "#fdecea"; statusText.style.color = "#c0392b"; statusText.innerText = "Legally Intoxicated (Above 0.08%)"; warningText.innerText = "Warning: You are over the legal limit for driving in most jurisdictions. Your judgment and motor skills are significantly impaired."; } else if (rawBAC >= 0.05) { resultBox.style.backgroundColor = "#fff9e6"; statusText.style.color = "#d68910"; statusText.innerText = "Moderate Impairment"; warningText.innerText = "Notice: You are approaching the legal limit. Reflexes and coordination are likely slowed."; } else if (rawBAC > 0) { resultBox.style.backgroundColor = "#eafaf1"; statusText.style.color = "#27ae60"; statusText.innerText = "Low Levels of Alcohol"; warningText.innerText = "Caution: Even small amounts of alcohol can affect reaction times."; } else { resultBox.style.backgroundColor = "#f4f6f7"; statusText.style.color = "#7f8c8d"; statusText.innerText = "System Likely Clear"; warningText.innerText = "Note: Calculated BAC is zero based on the time elapsed."; } }

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