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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.

Editorial note

This educational page is maintained by EtGCalc and reviewed against published EtG research, SAMHSA guidance, and our calculator methodology. It does not provide medical or legal advice.

Updated May 29, 2026Methodology & sources

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

You don't need to compute this manually. Our EtG Calculator does these steps automatically.

Related Reading

Molecular Breakdown

EtG Half-Life Calculator

Alcohol EtG Calculator

EtG vs BAC

Medical & Legal Disclaimer

Not Medical Advice

EtGCalc does not provide diagnosis, treatment, or medical advice. Talk with a qualified healthcare provider about alcohol use, metabolism, testing concerns, or recovery.

Not Legal Advice

EtG testing can affect probation, custody, licensing, and employment decisions. Consult a licensed attorney or your testing program for legal questions.

If You Need Support

In the United States, SAMHSA's National Helpline is 1-800-662-4357. It is free, confidential, and available 24/7.

Calculator output is an estimate, not a test prediction. Individual metabolism, hydration, kidney function, genetics, specimen handling, and lab cutoff policy can change real results. See our methodology and sources.

References

  1. 1
    SAMHSA. The Role of Biomarkers in the Treatment of Alcohol Use Disorders, 2012 Revision.

    Used for biomarker context, cutoff interpretation, and incidental exposure cautions.

  2. 2
    Jatlow et al. Ethyl glucuronide and ethyl sulfate assays in clinical trials, 2014.

    Used for urinary EtG and EtS kinetics after alcohol exposure.

  3. 3
    McDonell et al. Using ethyl glucuronide in urine to detect alcohol use, 2015.

    Used for EtG detection window context in clinical monitoring populations.

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