EtG 300 ng/mL Calculator

If you’ve received an EtG (ethyl glucuronide) urine test result and you’re trying to understand it against a 300 ng/mL cutoff — whether for a probation requirement, a treatment program, or your own knowledge — this guide walks through what the cutoff represents, how it compares with other EtG thresholds, and why a single number can’t tell the whole story on its own. If you’re new to EtG testing in general, our What Is EtG? guide is a good place to start before diving into cutoff specifics.

What is EtG testing?

Ethyl glucuronide (EtG) is a minor metabolite produced when the body breaks down alcohol. Because it can be detected in urine for longer than alcohol itself, EtG testing is widely used in settings where programs want insight into whether someone has consumed alcohol recently, even after any measurable blood alcohol has cleared.

Unlike a breathalyzer, which measures alcohol in the moment, an EtG urine test is a retrospective marker — it reflects exposure that may have occurred hours or in some cases a couple of days earlier, depending on the amount consumed, individual metabolism, hydration, and the cutoff concentration the laboratory applies. For a closer look at the lab process itself, see our guide on how EtG testing works.

What does a 300 ng/mL EtG result mean?

A “300 ng/mL EtG” reading refers to the concentration of EtG measured in a urine specimen, expressed in nanograms per milliliter. On its own, 300 ng/mL is just a number — its meaning only becomes useful once it’s compared against a cutoff: the threshold a laboratory or testing program uses to decide how a result should be classified.

When 300 ng/mL is used as the cutoff itself, a result below 300 ng/mL is reported as below that threshold, a result at exactly 300 ng/mL sits directly on the line, and a result above 300 ng/mL is at or above the threshold. What that classification actually means in practice — “negative,” “positive,” “inconclusive,” or something else — depends entirely on the rules of the specific testing program, not on the number alone.

Key point: EtG concentration is not a stopwatch. A 300 ng/mL reading doesn’t tell you exactly how many drinks were consumed or exactly when drinking occurred — it only tells you where the result falls relative to the chosen cutoff at the moment the specimen was collected.

EtG cutoff levels explained (100, 300, 500 ng/mL)

Different programs and laboratories have historically used different EtG cutoff levels, most commonly 100 ng/mL, 200 ng/mL, 300 ng/mL, 400 ng/mL, and 500 ng/mL. Published research comparing these thresholds has generally found a consistent pattern: lower cutoffs tend to be more sensitive (better at catching lower-level exposure) but less specific, while higher cutoffs tend to be more specific but less sensitive to lighter or more distant drinking.

Cutoff	General characteristic	Typical use case
100 ng/mL	Highest sensitivity, lowest specificity	Strict abstinence-monitoring programs
300 ng/mL	Moderate-to-lower sensitivity, higher specificity	Common intermediate cutoff in several programs
500 ng/mL	Lower sensitivity, higher specificity	Programs prioritizing fewer false positives

It’s worth repeating that these are general patterns from published comparisons, not universal rules — the exact cutoff, methodology, and interpretation used for any individual test is set by the specific laboratory or program, and that is always the authoritative source.

If your result needs to be checked against a different threshold, we also have dedicated tools for the 100 ng/mL EtG cutoff and the 200 ng/mL EtG cutoff, built the same way as the 300 ng/mL calculator.

Probation EtG cutoff: why the number can vary

EtG testing is frequently used in probation, court-ordered monitoring, and diversion programs as a way to check compliance with alcohol-abstinence conditions. However, there is no single, universal “probation EtG cutoff” that applies everywhere. Different courts, counties, and monitoring agencies contract with different laboratories, and those laboratories may apply different cutoff levels — 100, 200, 300, or 500 ng/mL are all used in various jurisdictions.

This matters because a result that would be classified one way under a 100 ng/mL program could be classified differently under a 300 ng/mL or 500 ng/mL program. If you are being tested as part of probation or a similar legal requirement, the only reliable source for the cutoff that applies to you is your probation officer, the court order, or the laboratory report itself — not a general assumption about “the” EtG cutoff.

Good practice: Ask directly (or check your program paperwork) which cutoff level applies to your specific testing requirement, and whether the program uses immunoassay screening, confirmatory testing, or both — this affects how a borderline result near 300 ng/mL is ultimately handled.

For background on how alcohol biomarkers like EtG are meant to be used in treatment and monitoring settings, the U.S. Substance Abuse and Mental Health Services Administration has published a detailed advisory: The Role of Biomarkers in the Treatment of Alcohol Use Disorders (SAMHSA, 2012 Revision). It’s a useful outside reference if you want to read how a federal agency frames the strengths and limits of EtG testing.

EtG 300 vs 500: what’s the difference?

The core difference between a 300 ng/mL and a 500 ng/mL EtG cutoff is simply the concentration threshold being applied — 500 ng/mL is a higher bar than 300 ng/mL. Practically, that means:

• A result that falls between 300 and 500 ng/mL would be classified as above cutoff under a 300 ng/mL program, but below cutoff under a 500 ng/mL program.
• Programs using a 500 ng/mL cutoff are generally designed to reduce the chance of flagging very light, incidental, or non-beverage alcohol exposure (such as some hand sanitizers, mouthwash, or certain foods) compared with lower cutoffs.
• Programs using a 300 ng/mL cutoff sit in between the more sensitive 100 ng/mL threshold and the more specific 500 ng/mL threshold, balancing the two differently.

Neither cutoff is universally “correct” — each represents a different trade-off between catching lower-level exposure and minimizing results driven by incidental, non-drinking sources of alcohol. The comparison table inside the calculator shows exactly where your specific result falls relative to both 300 ng/mL and 500 ng/mL at the same time.

How long until EtG is under 300 ng/mL?

This is one of the most searched EtG questions, and honestly, it’s the one with the least precise answer. There is no fixed, universal elimination rate that lets anyone reliably predict exactly how many hours it will take for a person’s EtG concentration to fall below 300 ng/mL. Detection windows reported in research and clinical literature vary widely — commonly cited ranges span roughly a day up to several days after heavier drinking — because the actual timeline depends on a combination of factors:

• Amount of alcohol consumed and drinking pattern (single episode vs. sustained drinking)
• Individual metabolism and liver function
• Body composition, hydration, and urine concentration at the time of collection
• Kidney function and overall fluid intake
• The specific cutoff and assay method used by the testing laboratory

Because of this variability, our calculator intentionally does not convert a number of drinks or hours elapsed into a predicted “time until under 300 ng/mL.” Any tool that promises an exact countdown to a specific EtG number is presenting a level of precision that current research does not actually support for individual predictions.

Using the EtG 300 calculator

The calculator on this page is built for one specific job: taking an EtG concentration you already have — from a lab report — and showing you clearly where it sits relative to the 300 ng/mL cutoff, as well as the 100 ng/mL and 500 ng/mL thresholds for context.

1. Enter the EtG number exactly as reported by your laboratory.
2. The tool instantly compares it against the fixed 300 ng/mL cutoff.
3. A side-by-side table also shows the same result against 100 ng/mL and 500 ng/mL.
4. Optional context fields (drinks, weight, sex, hours since last drink) are there for your own reference — they are not used to generate a predicted future EtG level, for the accuracy reasons explained above.

For any decision tied to probation, court requirements, employment, or treatment, always defer to the actual laboratory report and the specific rules of your testing program.

Want a broader estimate that factors in more variables, or need to check a different cutoff entirely? Try our standard ETG Calculator, the Advanced ETG Calculator for more detailed inputs, or browse the full set of EtG testing guides for more background reading.

Frequently asked questions

What is a good EtG cutoff level? There isn’t a single “good” or “correct” cutoff — 100, 300, and 500 ng/mL are all used by different programs, each balancing sensitivity (catching lighter exposure) against specificity (avoiding false positives) differently. The right cutoff is whichever one your specific laboratory or testing program has adopted.

Does a 300 ng/mL EtG result always mean I drank alcohol? Not necessarily. While EtG is a specific marker of alcohol exposure, results can theoretically be influenced by incidental exposure sources in some cases, and interpretation also depends on the testing method and confirmatory steps used. A single number should be read in context by the relevant program, not treated as automatic proof on its own.

Is the EtG cutoff the same for every probation program? No. EtG cutoff levels used in probation and court-monitoring contexts vary by jurisdiction and by the laboratory each program contracts with. Some use 100 ng/mL, others use 300 ng/mL or 500 ng/mL. Always check your specific program’s paperwork or ask your supervising officer.

What’s the real difference between EtG 300 and 500? 500 ng/mL is simply a higher concentration threshold than 300 ng/mL. A result between 300–500 ng/mL would be classified differently depending on which of the two cutoffs the testing program applies — above cutoff under a 300 ng/mL rule, below cutoff under a 500 ng/mL rule.

How long does it take for EtG to drop below 300 ng/mL? There’s no single fixed timeline. It depends on how much alcohol was consumed, individual metabolism, hydration, and urine concentration, among other factors. Because of that variability, this page does not offer a specific predicted countdown — only an interpretation of a result you already have.

Can I use this EtG 300 calculator for legal or probation decisions? This calculator is an educational tool meant to help you read and compare a reported EtG number. It is not a substitute for the official laboratory report or the specific requirements of a probation, court, treatment, or employment program, all of which should be treated as the authoritative source.

How accurate are EtG calculators in general? EtG calculators are estimation tools, not laboratory tests — their accuracy depends on the assumptions and data behind them. For a full breakdown of what affects reliability, see our guide, How Accurate Is an EtG Calculator?

Important disclaimer

This article and the accompanying calculator are provided for general educational and informational purposes only. They do not diagnose alcohol use, determine exactly when or how much alcohol was consumed, predict an individual’s future EtG concentration, or guarantee how any laboratory, probation, court, treatment, or employment program will interpret a result. Actual EtG outcomes can vary substantially due to individual biology, drinking pattern, urine concentration, specimen timing, laboratory method, and the cutoff used by the relevant program. For legal, probation, employment, treatment, or medical decisions, always rely on the official laboratory result and the requirements of the applicable program.

Research note: Published research on urinary EtG has evaluated cutoff concentrations including 100, 200, 300, 400 and 500 ng/mL, generally finding that lower cutoffs increase sensitivity while higher cutoffs increase specificity. This summary draws on publicly available findings, including the SAMHSA Advisory on alcohol biomarkers, for educational purposes only, and does not replace guidance from a laboratory, medical professional, attorney, or supervising program.