ETG Calculator — EtG Detection Window

How to Use ETG Calculator — EtG Detection Window

1. Step 1: Enter Drinks

   Type your total standard drinks for the episode (U.S. standard ≈ 14 g alcohol).

2. Step 2: Set Timing

   Enter hours since your last drink ended. Use the end of the episode.

3. Step 3: Pick Cutoff & Pattern

   Choose the urine EtG cutoff (100–1000 ng/mL) and drinking pattern (single, heavy, chronic).

4. Step 4: Review Window & Status

   See the estimated detection window, current assessment, and likelihood bar.

Key Features

• Estimated detection window range
• Cutoff sensitivity: 100–1000 ng/mL
• Patterns: single, heavy, chronic
• Current assessment + likelihood bar
• Mobile‑first inputs and summaries

Understanding Results

Formula (plain language)

This ETG calculator estimates a detection window by combining three inputs: your total standard drinks, hours since your last drink ended, and the urine EtG cutoff used by the laboratory. In general, more drinks and more frequent use extend the window; lower cutoffs (for example 100–300 ng/mL) also extend it, while higher cutoffs (for example 1000 ng/mL) shorten it. The result is an earliest and latest time range after your last drink when EtG may be detectable, plus a simple likelihood indicator if you tested now.

Reference ranges & interpretation

Common patterns at a 500 ng/mL cutoff are: 1–2 drinks ≈ 12–24 hours; 3–5 drinks ≈ 24–48 hours; heavier single episodes ≈ 36–60+ hours; and very heavy or repeated use up to ~72–80+ hours. At 100 ng/mL, detection can extend a day or more beyond those bounds. Actual timing varies with hydration, urine concentration, collection timing, organ function, and laboratory method. Use these ranges as guardrails rather than guarantees.

Assumptions & limitations

This tool provides educational estimates and does not offer medical or legal advice. Urine dilution, kidney and liver function, chronic heavy use, confirmatory testing, and lab‑specific procedures (including creatinine correction) can change results. Only the laboratory report is definitive.

Complete Guide: ETG Calculator — EtG Detection Window

Use our ETG calculator to estimate urine ethyl glucuronide detection windows by drinks consumed, hours since last drink, and lab cutoffs from 100 to 1000 ng/mL.

This ETG calculator estimates the likely detection window for ethyl glucuronide (EtG) in urine after drinking alcohol. It models how your total standard drinks, the time since your last drink, and the laboratory cutoff threshold (for example 100, 200, 300, 500, or 1000 ng/mL) shift the window of detection. Results are heuristic and educational — they do not replace a laboratory test, medical judgment, or legal guidance.

How EtG testing works

When your body metabolizes alcohol (ethanol), small fractions are converted into measurable metabolites. Two of the most widely used markers in urine are ethyl glucuronide (EtG) and ethyl sulfate (EtS). These conjugated molecules last longer than ethanol itself, making them useful for detecting recent alcohol use. While a breath or blood alcohol test might drop to zero within hours, EtG and EtS may remain detectable for one to several days, depending on how much you drank, how often you drink, and how sensitive the laboratory method is.

Laboratories report EtG in nanograms per milliliter (ng/mL). Common urine cutoffs include 100, 200, 300, 500, and 1000 ng/mL. Lower cutoffs are more sensitive and can catch smaller amounts or older drinking, while higher cutoffs trade sensitivity for specificity. Many programs prefer 500 ng/mL to reduce the chance that incidental exposure (for example mouthwash) triggers a positive, but local policy and clinical context vary.

What our ETG calculator estimates

The calculator models an estimated detection window — an earliest and latest time (in hours after your last drink) when EtG could be detected at the cutoff you choose. You enter the total number of standard drinks, choose the drinking pattern (single occasion, heavy episode, or chronic daily use), select the lab cutoff, and enter the hours since you finished drinking. The tool then displays:

• Earliest clear time: the lower bound of when EtG is likely to fall below the cutoff.
• Latest likely clear time: a cautious upper bound (long tail) based on pattern and cutoff.
• Current assessment: likely positive, possibly positive, borderline near the cutoff, or likely negative.
• Heuristic likelihood bar: a simple visual showing how detection probability tends to drop over time.

These ranges are drawn from published detection patterns and practical guardrails: roughly 12–24 hours after one or two drinks at 500 ng/mL; 24–48 hours with three to five drinks; 36–60+ hours after heavier single episodes; and up to ~72–80+ hours for very heavy or repeated use. At 100 ng/mL, the window can extend a day or more beyond those estimates. For chronic daily use, the tail may extend further.

Standard drink definition

In the United States, one standard drink contains about 14 grams of pure alcohol. That’s roughly a 12 oz beer at 5% ABV, a 5 oz glass of wine at 12% ABV, or a 1.5 oz shot of 40% ABV spirits. Different countries use different definitions, so if you’re outside the U.S., consider the local standard. The calculator uses the U.S. definition when you enter the number of standard drinks.

Cutoff thresholds and sensitivity

Lower cutoffs (like 100 or 200 ng/mL) make a test more sensitive — the lab can detect smaller traces of EtG, and for longer after drinking. The trade‑off is a higher chance that non‑beverage exposures (for example, products that contain alcohol) could register above the cutoff. Higher cutoffs (like 500 or 1000 ng/mL) shorten the window but reduce the odds that incidental exposure leads to a reportable positive.

Programs often choose 500 ng/mL as a balance of sensitivity and specificity, but protocols differ. Our tool lets you explore how the window shifts if a lab uses a more sensitive (100–300) or more specific (1000) cutoff.

Factors that shift detection

Even with identical drinking amounts, two people can show different EtG timelines. Hydration status and urine dilution, kidney and liver function, timing of urine collection, repeated use over several days, body size, and the specific laboratory method (immunoassay versus LC/MS with different cutoffs) all matter. The calculator incorporates conservative adjustments for “heavy episodes” and “chronic daily use” to reflect longer tails seen in practice.

If you’re comparing EtG estimates with breath or blood alcohol calculations, note that these tests answer different questions. A BAC calculator estimates impairment from ethanol itself (hours), whereas EtG is a metabolite that can linger for days. If you want to quantify your intake precisely, ourAlcohol Units calculatorand Alcohol calculator can help you tally standard drinks.

Using results responsibly

Treat the output as an educational estimate, not as clearance to take a test, drive, work, or meet any formal requirement. Only the actual laboratory result is definitive. If your program or clinician uses a different cutoff or a confirmatory method, your window may differ from the ranges shown here. For general wellness, tools like our Hydration calculatorand Water Intake calculatorcan support recovery days by helping you plan fluid targets (note that hydration can dilute urine and affect measured concentrations, but policies vary on how labs handle dilution and creatinine correction).

If you’re tracking organ health over time, ourLiver Function calculatorand Kidney Function calculator provide general education about common lab markers. And if you’re curious how long a medicine might persist, the Drug Half‑Life calculator explains exponential decay and the “five half‑lives” rule of thumb.

Incidental exposure myths

Everyday products — mouthwash, hand sanitizer, certain foods — can contain alcohol. Sensitive cutoffs (for example 100 ng/mL) could, in some circumstances, register an incidental exposure, but most programs use counseling and context to distinguish incidental exposure from beverage alcohol use. Higher cutoffs (for example 500 ng/mL) are chosen specifically to reduce incidental positives. Always follow your program’s guidance and product use policies.

Professional guidance on interpretation and cutoff selection is available in public health resources (for example, the U.S. National Institute on Alcohol Abuse and Alcoholism and clinical toxicology texts). For high‑ stakes questions, defer to your clinician and the laboratory’s written methods and reference documents.

Why labs often pair EtG and EtS

EtG and EtS form through different biochemical pathways. Measuring both can strengthen interpretation because each has distinct interferences and stability characteristics. If one marker appears low due to degradation or handling, the other may still provide evidence of recent drinking. Many laboratories screen with an immunoassay and then confirm positive results via liquid chromatography with mass spectrometry at a defined cutoff.

Our calculator focuses on EtG because it is the most commonly referenced marker in program policies. However, an actual report could include EtS and a creatinine‑normalized value. If you see creatinine correction discussed in your report, it reflects an attempt to account for urine concentration, which can vary with hydration and timing.

Scenario walk‑throughs

Consider three simplified examples. First, a person has two standard drinks on a Friday evening, finishing at 9 p.m., and faces a 500 ng/mL test. Many would be negative by late Saturday, roughly 12–24 hours later, assuming normal hydration and organ function. Second, a person has six drinks at a party, finishing at midnight, with a 500 ng/mL test. Detection could extend into Sunday afternoon or later (36–60+ hours). Third, a person who drinks daily over a week may show a longer tail — even if a final episode is modest — because metabolites and physiological effects accumulate. In a sensitive program using 100 ng/mL, each window extends further.

The calculator tries to capture these patterns by letting you select a drinking pattern and cutoff. For planning purposes, always err on the conservative side, especially if your program uses sensitive cutoffs or confirms at lower thresholds.

Cutoff selection in programs

Cutoff policies differ between clinical monitoring, workplace programs, and legal settings. A clinician who is monitoring recovery may prefer a sensitive approach (100–300 ng/mL) to catch slips early and guide care. A workplace or court program might adopt 500 ng/mL or higher to reduce the chance of incidental positives from non‑beverage sources. Some programs specify a screening cutoff and a separate confirmatory cutoff with a more specific analytic method. Read your policy documents — they govern how results are interpreted.

Urine dilution and creatinine correction

Drinking more water dilutes urine and can lower measured EtG concentration, but most labs track specimen validity and may normalize results to creatinine or flag samples as abnormally dilute. That means hydration can change numbers, but it does not automatically convert a true positive to a true negative. Focus on healthy hydration for recovery and wellbeing rather than attempting to manipulate a lab value.

How EtG compares with other alcohol biomarkers

EtG/EtS are designed to capture recent drinking over the last several days. Breath or blood alcohol tests detect impairment‑scale ethanol for a shorter window (hours). In contrast, blood phosphatidylethanol (PEth) can reflect sustained use over weeks, and hair or nail tests can reflect longer‑term patterns. Each biomarker has its place. Our calculator addresses only the short‑term urine EtG window, which is the most commonly used in frequent monitoring.

As a practical rule, pair the tools you need for your question. For “how many drinks was that?”, use theAlcohol calculator orAlcohol Units calculator. For safety and impairment timing questions, check the BAC calculator. For wellness habits during a break, see Hydration andWater Intake tools. For lab literacy, look atLiver Function andKidney Function.

Next steps and helpful tools

If you need more context around your intake, start with the Alcohol Units calculator to convert different beverages into standard drinks, then review impairment timing in the BAC calculator. To plan a low‑alcohol period, pair this tool with the Hydration calculator and Water Intake calculator. For lab literacy, explore the Liver Function and Kidney Function pages.

External resources: NIAAA (alcohol science) and program‑level EtG policy briefs from public health agencies.

Frequently Asked Questions