The Quick Answer
Your body eliminates ETG at a predictable rate. The formula is simple: your ETG level drops by half every 2-3 hours. That's the core of every ETG calculator, including ours.
- ETG follows exponential decay with a half-life of 2-3 hours
- Peak ETG occurs about 2-3 hours after your last drink
- Detection time depends on amount consumed and test sensitivity
Try it now — enter your details below:
Quick ETG Check
Instant estimation (No data saved)
High Probability of Detection
Estimated 10 more hours until low risk (<100ng/mL).
*This is an estimation only. Individual results vary. Not legal or medical advice.
The Half-Life Decay Formula
Here's the exact formula used in our ETG Calculator:
ETG(t) = Peak × 0.5^(t / half-life)This exponential decay formula calculates your estimated ETG level at any point in time. As time passes, your ETG concentration drops by half every 2-3 hours.
Variables
ETG(t)Current Level
Your estimated ETG concentration at time t (in ng/mL)
PeakPeak ETG
Maximum ETG produced after drinking (typically 5,000-10,000 ng/mL per drink)
tTime Elapsed
Hours since peak (about 2-3 hours after your last drink)
half-lifeHalf-Life
Time for ETG to reduce by 50% (typically 2-3 hours)
How the Calculation Works
Let's break down the formula into simple steps:
Step 1: Estimate Peak ETG
When you drink alcohol, your liver converts it into ETG (Ethyl Glucuronide). The amount produced depends on how much you drank:
| Drinks | Estimated Peak ETG |
|---|---|
| 1-2 drinks | 5,000-15,000 ng/mL |
| 3-4 drinks | 15,000-30,000 ng/mL |
| 5-6 drinks | 30,000-50,000 ng/mL |
| 7+ drinks | 50,000+ ng/mL |
Peak ETG typically occurs 2-3 hours after your last drink—not when you stop feeling drunk.
Step 2: Apply the Decay Formula
Once ETG peaks, it starts declining. The half-life (time to drop by 50%) is approximately 2-3 hours for most people.
Example calculation:
- You had 4 drinks (Peak: ~20,000 ng/mL)
- After 3 hours: 20,000 × 0.5 = 10,000 ng/mL
- After 6 hours: 10,000 × 0.5 = 5,000 ng/mL
- After 9 hours: 5,000 × 0.5 = 2,500 ng/mL
- After 12 hours: 2,500 × 0.5 = 1,250 ng/mL
Step 3: Compare to Test Cutoff
Your result depends on which cutoff threshold the test uses:
| Cutoff | Common Use | At 1,250 ng/mL |
|---|---|---|
| 500 ng/mL | Employment, standard tests | ❌ Fail |
| 100 ng/mL | Probation, court-ordered | ❌ Fail |
In this example, you'd need to wait longer. Let's continue:
- After 15 hours: ~625 ng/mL (still failing 500)
- After 18 hours: ~312 ng/mL (passing 500, failing 100)
- After 24 hours: ~78 ng/mL (passing both)
What Affects Your Results
The formula uses averages. Your actual results may vary by 20-30% based on:
Metabolism Speed
Some people process ETG faster than others. Factors include:
- Liver health — healthier liver = faster processing
- Age — metabolism slows with age
- Genetics — enzyme variations affect clearance rate
Body Composition
- Body weight — larger bodies have more fluid volume, diluting ETG
- Hydration — well-hydrated = more dilute urine samples
- Sex — women typically show higher peak ETG than men for same amount
The Alcohol Itself
- Drink strength — a strong craft beer counts as 1.5+ standard drinks
- Food intake — eating slows alcohol absorption, affecting peak timing
- Drinking speed — rapid consumption = higher peak ETG
Important Limitations
Our calculator provides estimates, not guarantees. Here's what it can't account for:
- Individual variation — your metabolism might be 30% faster or slower than average
- Test accuracy — lab equipment has its own margin of error
- Sample timing — urine concentration varies throughout the day
- Incidental exposure — hand sanitizers, mouthwash can add small amounts
Always add buffer time. If the calculator says you'll clear in 10 hours, wait 15 to be safe.
The Science Behind It
This formula isn't something we invented. It's based on peer-reviewed research:
- Wurst FM et al. (2006) — "Ethyl glucuronide: update" in Forensic Science International
- Helander A, Beck O (2005) — "Ethyl sulfate: a metabolite of ethanol" in Clinical Chemistry
- SAMHSA Guidelines — Standard cutoff recommendations for ETG/ETS testing
Our calculator implements these findings transparently. Unlike some competitors who hide their algorithms, we show you exactly how it works.
Related Resources
- ETG Calculator — Run your own calculation
- ETG Detection Time Chart — Visual breakdown by drinks
- Realistic ETG Detection Times — In-depth guide to detection windows
The formula is based on medical research and provides a solid estimate. However, individual variation means your actual results could be 20-30% different. Factors like liver health, body weight, and genetics all play a role. For important tests, always add extra buffer time beyond what the calculator shows.
Medical studies have found that ETG elimination follows first-order kinetics with a half-life typically between 2-3 hours. This can vary slightly based on individual factors, which is why our calculator uses the research average. Some people may clear faster (2 hours) while others slower (3+ hours).
No. Your liver processes ETG at a fixed rate regardless of hydration, exercise, or supplements. Drinking lots of water only dilutes your urine sample—it doesn't speed up metabolism. In fact, overly dilute samples are often flagged by labs and may require a retest.
The cutoff threshold determines how sensitive the test is. Standard employment tests typically use 500 ng/mL—you'll pass if your level is below this. Court-ordered and probation tests often use 100 ng/mL, which can detect drinking from much longer ago. The same ETG level could pass one test and fail another.
This page is for educational purposes only. It does not constitute medical or legal advice. Individual results vary significantly. Consult a healthcare provider or legal professional for guidance specific to your situation.