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How to Calculate EtG Levels

A comprehensive guide to understanding Ethyl Glucuronide (EtG) calculation, the science behind it, and what factors affect your results.

Quick Summary

EtG is a direct metabolite of alcohol detectable in urine for 24-80 hours after drinking. Our calculator uses the Widmark formula combined with EtG decay research to estimate your current levels and clearance time.

1Understanding Standard Drinks

Before calculating EtG, you need to convert your alcohol consumption into standard drinks. One standard drink in the US contains approximately 14 grams of pure alcohol.

🍺
Beer
12 oz at 5% ABV
🍷
Wine
5 oz at 12% ABV
🥃
Liquor
1.5 oz at 40% ABV

2The Widmark Formula

The Widmark formula calculates Blood Alcohol Concentration (BAC) based on body weight, gender, and alcohol consumed:

BAC = (Alcohol in grams) / (Body weight × r)

Where r is the Widmark factor:

Male
r = 0.68
Female
r = 0.55

3From BAC to EtG

EtG (Ethyl Glucuronide) is produced when your liver processes alcohol. Key facts:

  • Peak EtG occurs 9-12 hours after peak BAC
  • Conversion ratio: ~3,500 ng/mL per 0.01% BAC (average)
  • Half-life: 2.5-3 hours (EtG decays exponentially)

4Cutoff Thresholds

Different testing scenarios use different cutoff levels:

500 ng/mL
Standard cutoff - Recent heavy drinking
100-500 ng/mL
Low positive - Light/moderate drinking
<100 ng/mL
Negative - No recent drinking or incidental exposure

5Factors That Affect Results

Individual Factors

  • • Body weight and composition
  • • Biological sex
  • • Liver function and health
  • • Hydration levels
  • • Genetic variations in metabolism

Consumption Factors

  • • Type and amount of alcohol
  • • Drinking pattern (binge vs. spread out)
  • • Food consumption
  • • Time since last drink
  • • Frequency of drinking

Ready to Calculate?

Use our free EtG calculator to estimate your current levels and clearance time based on your specific situation.

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