An EtG test doesn’t measure how much you drank. It detects a byproduct of alcohol metabolism in your urine and flags whether you consumed any alcohol recently, but it cannot reliably distinguish between three drinks and ten. That said, the amount you drink directly affects how long EtG stays detectable and how high your levels climb, which is why labs use different cutoff thresholds to separate likely heavy drinking from lighter or incidental exposure.
How the EtG Test Works
When your body processes alcohol, about 0.5% of it gets converted into a compound called ethyl glucuronide, or EtG. This is a tiny fraction of total alcohol metabolism, but EtG lingers in your urine long after alcohol itself has cleared your system. A standard breathalyzer or blood alcohol test is useless after 12 hours. EtG can remain detectable for up to 48 hours after a few drinks, and 72 hours or longer after heavier drinking.
That extended detection window is the whole point. EtG tests are used in situations where someone needs to prove abstinence over days, not hours: court-ordered sobriety monitoring, professional licensing programs, substance abuse treatment, and workplace compliance. The test isn’t asking “are you drunk right now?” It’s asking “did you drink at all in the last few days?”
The Two Cutoff Levels
Most labs use one of two cutoff thresholds, and which one applies to you changes what counts as a positive result.
- 100 ng/mL: This is the more sensitive cutoff. It catches any recent alcohol exposure, including very light drinking. Labs and monitoring programs that require strict abstinence typically use this threshold.
- 500 ng/mL: This higher cutoff is designed to reduce false positives from incidental exposure (hand sanitizer, mouthwash, certain foods). A result above 500 ng/mL is generally interpreted as strong evidence of intentional alcohol consumption, and in many monitoring programs, it’s treated as a marker of heavier or more recent drinking.
If your program uses the 500 ng/mL cutoff, a single beer consumed 24 hours earlier might not trigger a positive. At the 100 ng/mL cutoff, that same beer likely would. The cutoff your program uses matters enormously, and you should know which one applies to your situation.
What “Heavy Drinking” Looks Like on an EtG Test
Heavy drinking for EtG purposes is generally considered 10 or more standard drinks. At that level, using a 100 ng/mL cutoff, detection is likely for 24 to 48 hours after your last drink and remains possible for 48 to 60 hours. Even at 60 to 72 hours, a positive result isn’t impossible, though it becomes fairly unlikely. By 72 to 80 hours, detection is unlikely regardless of how much you drank.
Compare that to light drinking of one to four drinks. At the same 100 ng/mL cutoff, detection is likely only within the first 12 hours. By 12 to 24 hours, it could go either way. After 36 hours, a positive becomes unlikely. So the practical difference between heavy and light drinking isn’t a specific EtG concentration on your lab report. It’s how many days later the test can still catch you.
Why the Test Can’t Tell You How Much Someone Drank
This is the part that surprises most people. Despite the different cutoff levels, EtG concentrations in urine do not reliably correlate with the amount of alcohol consumed. Two people can drink the same amount and produce very different EtG levels. Several factors drive this variation.
Hydration is the biggest one. If you’re well-hydrated and producing dilute urine, your EtG concentration drops. If you’re dehydrated, the same amount of EtG is packed into less fluid, and your levels read higher. Kidney function, individual metabolism, body composition, and even genetic differences in the liver enzymes that produce EtG all play a role. Researchers have found that normalizing EtG levels against creatinine (a marker of urine concentration) improves accuracy somewhat, but even then, pinpointing exact drink counts from a urine sample is not scientifically reliable.
This is why monitoring programs treat EtG as a yes-or-no indicator of exposure rather than a breathalyzer-style measurement. A very high result suggests heavier or more recent drinking, but a moderate result doesn’t necessarily mean moderate drinking.
False Positives From Non-Beverage Sources
EtG tests are sensitive enough to pick up alcohol you never intended to consume. Hand sanitizers containing propyl alcohol have produced false-positive results on immunoassay screening tests at levels well above the 100 ng/mL cutoff. In one study, normal use of a propyl alcohol-based sanitizer produced EtG readings up to 4,000 ng/mL on initial screening, and even passive inhalation of sanitizer vapor triggered positive results. These false positives persisted up to six hours after the last contact with the sanitizer.
Alcohol-containing mouthwash, certain medications, fermented foods, and kombucha can also produce low-level positive results. Some cleaning products and cosmetics contain alcohol that absorbs through the skin.
This is one reason the 500 ng/mL cutoff exists: it filters out most incidental exposures. It’s also why confirmatory testing matters. The initial screening test (immunoassay) is faster but less specific, and can cross-react with compounds that aren’t actually EtG. When a positive result is disputed, labs run a confirmation test using mass spectrometry, which identifies EtG specifically and eliminates false positives from other substances.
What This Means If You’re Being Tested
If you’re in a monitoring program, the practical takeaway is that any alcohol consumption carries detection risk for two to three days, and heavy drinking extends that window. Drinking 10 or more drinks on a Friday night could still produce a positive result on Monday morning. Four drinks on Friday is less likely to show up by Monday, but it’s not guaranteed to be clear either, especially at the 100 ng/mL threshold.
You should also know that “heavy drinking” in a clinical sense is defined differently than it is for EtG testing. Public health guidelines define heavy drinking as 15 or more drinks per week for men, or 8 or more for women. But for EtG monitoring, the relevant question is how many drinks you had in a single episode, because that determines your detection window. A single night of 10 drinks is more likely to trigger a positive test days later than spreading 10 drinks across an entire week.
If you’re concerned about incidental exposure, avoid alcohol-based hand sanitizers, mouthwash containing ethanol, and other products with alcohol on the ingredient list in the days before your test. If you do test positive and believe it’s a false positive, ask whether confirmatory testing by mass spectrometry was performed. Initial immunoassay screening can be triggered by substances other than EtG, and confirmation testing is the only way to rule that out definitively.