How to Read the ETG Detection Time Chart
Stressed about an upcoming test? You're not alone. The ETG Detection Time Chart helps you understand where you stand—but it can be confusing at first glance.
Need a quick answer? Jump to the calculator below, or keep reading to understand what the chart actually means.
- The chart shows estimated ETG levels decreasing over time
- Colors indicate risk levels: green (safe), yellow (uncertain), red (high risk)
- Two lines show different cutoff thresholds (500 ng/mL vs 100 ng/mL)
- Your position on the chart depends on how much you drank and when
Quick Calculator
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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.
Now let's break down what the chart actually shows.
Understanding the Axes
The X-Axis: Time Since Last Drink
The horizontal axis shows hours elapsed since your last alcoholic drink. This is the most critical variable in ETG detection.
Key points:
- Time starts from when you stopped drinking, not when you started
- ETG levels peak 4-6 hours after your last drink
- The chart typically spans 0-80+ hours
The Y-Axis: ETG Concentration
The vertical axis shows ETG concentration measured in nanograms per milliliter (ng/mL). This is what the lab measures in your urine sample.
Understanding the scale:
- After drinking, ETG can spike to 10,000-50,000+ ng/mL
- The chart often uses a logarithmic scale (each step is 10× the previous)
- What matters is whether you're above or below the cutoff line
For the math behind these numbers, see our ETG calculation formula guide.
What the Colors Mean
The chart uses color coding to quickly show your detection risk level:
Low Risk
Below CutoffETG levels are below the testing threshold. Detection is unlikely on standard tests.
Example: Likely to pass employment and standard probation tests.
Uncertain
Near CutoffETG levels are in the borderline zone. You might pass a 500 ng/mL test but fail a 100 ng/mL test.
Example: Risk varies by test sensitivity and individual factors.
High Risk
Above CutoffETG levels are significantly elevated. Detection is very likely on any standard test.
Example: High probability of positive result on most tests.
Important: These zones are estimates. Individual variation means your actual risk may differ by 20-30% from what the chart shows.
The Two Lines Explained
Most ETG charts show two horizontal lines representing different test sensitivities. Understanding which applies to you is crucial.
Quick Comparison: 500 vs 100 ng/mL
| Cutoff | Who Uses It | Detection Window | Risk Level |
|---|---|---|---|
| 500 ng/mL | DOT tests, most employers | 24-60 hours | More forgiving |
| 100 ng/mL | Probation, court orders, treatment programs | 48-80+ hours | Very strict |
The 500 ng/mL Line (Standard)
This is the standard cutoff used by most testing programs:
- Used for: Department of Transportation (DOT) tests, most employment screenings
- Detection window: Generally shorter (24-60 hours depending on consumption)
- More forgiving: You'll drop below this threshold faster
If your test uses a 500 ng/mL cutoff, focus on being below this line.
The 100 ng/mL Line (Strict)
This is the strict cutoff used for intensive monitoring:
- Used for: Probation, court-ordered testing, some treatment programs
- Detection window: Longer (48-80+ hours depending on consumption)
- More sensitive: Even small amounts of alcohol can be detected longer
If you're on probation or court-ordered monitoring, assume your test uses this cutoff unless told otherwise. Learn more about ETG test cutoff levels.
How to Use the Chart for Your Situation
Follow these steps to estimate your risk:
- Know Your Drinking Amount — Count your standard drinks accurately:
- 1 beer (12 oz, 5% ABV) = 1 standard drink
- 1 glass of wine (5 oz, 12% ABV) = 1 standard drink
- 1 shot (1.5 oz, 40% ABV) = 1 standard drink
- Find Your Time Point — Calculate hours since your last drink. Be precise—hours matter significantly.
- Locate Your Position — Find where your drinking amount and elapsed time intersect on the chart. Note which color zone you're in.
- Check Your Cutoff — Determine which line applies to your test (500 ng/mL or 100 ng/mL) and see if you're above or below it.
Want a personalized calculation? Try our full ETG Calculator for detailed results.
Common Mistakes When Reading the Chart
Mistake 1: Assuming the Chart is Exact
The chart shows averages. Your actual ETG levels could be 20-30% higher or lower due to:
- Individual metabolism differences
- Liver health and function
- Hydration levels
- Body composition
Solution: Add buffer time. If the chart says you'll be clear in 48 hours, plan for 60.
Mistake 2: Using the Wrong Cutoff
Many people assume all tests use 500 ng/mL. Court-ordered and probation tests often use 100 ng/mL—a 5× more sensitive threshold.
Solution: Ask your testing administrator about your specific cutoff level before making assumptions.
Mistake 3: Forgetting Peak Delay
ETG doesn't peak immediately. Levels continue rising for 4-6 hours after your last drink, then begin declining.
Solution: Count from when you stopped drinking, and remember the first few hours show increasing—not decreasing—levels.
Mistake 4: Ignoring the Confidence Interval
Being "just below" the line doesn't mean you're safe. There's inherent variation in both your metabolism and the test itself.
Solution: Aim to be well below your cutoff, not just barely under it.
Factors That Shift Your Position
Several factors can move your actual levels higher or lower than the chart predicts:
Factors that may extend detection time:
- Slower metabolism (older age, liver issues)
- Higher body fat percentage
- Chronic heavy drinking (enzyme changes)
- Dehydration at test time
Factors that may shorten detection time:
- Faster metabolism (younger, healthier liver)
- Higher muscle mass
- Proper hydration
For detailed information, see our guide on factors affecting ETG levels.
When to Trust the Chart (and When Not To)
The chart is useful for:
- General planning and risk awareness
- Understanding how consumption amount affects detection
- Comparing relative risk between scenarios
The chart should NOT be used to:
- Make guarantees about test results
- Justify drinking close to test dates
- Replace professional advice in legal situations
Related Resources
- ETG Detection Time Chart — Interactive chart tool
- ETG Calculator — Personalized detection estimates
- ETG Test Cutoff Levels — Understanding thresholds
- ETG Calculation Formula — The math behind the estimates
The two lines represent different cutoff thresholds used by various testing programs. The 500 ng/mL line is the standard cutoff for employment and DOT tests. The 100 ng/mL line is the stricter cutoff used for probation, court-ordered, and some treatment program tests. Which line applies depends on your specific testing situation.
No. The chart shows population averages based on clinical studies. Individual variation is significant—your actual ETG levels could be 20-30% higher or lower than predicted. Factors like metabolism, liver health, body composition, and hydration all affect results. Always add buffer time for important tests.
If you're between the 500 ng/mL and 100 ng/mL lines, you would likely pass a standard employment test but might fail a strict probation test. This is the 'uncertain' zone where outcomes depend heavily on your specific cutoff and individual variation. When in doubt, wait longer.
The chart is most useful as a planning tool before drinking, not after. Check it to understand how different drinking amounts will affect your detection window. Once you've consumed alcohol, use our ETG calculator for a more personalized estimate based on your specific situation.
We strongly advise against trying to 'time' drinking around tests. The chart shows averages with significant individual variation. If you have regular testing obligations, the safest approach is complete abstinence. If you need support, visit our Get Help page for resources.
This page is for educational purposes only. It does not constitute medical or legal advice. Individual results vary significantly. The chart provides estimates based on population averages and should not be used as a guarantee of test results. Consult a healthcare provider or legal professional for guidance specific to your situation.