EtG Alcohol Detection Calculator

Drinking pattern	500 ng/mL cutoff	100 ng/mL (sensitive) cutoff
Light (< 2 drinks)	12–24 hours	up to 24–36 hours
Moderate (2–4 drinks)	24–48 hours	up to 48–60 hours
Heavy (> 4 drinks)	48–72 hours	up to 72–80 hours

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Walk-through

How to Use This Calculator

4 steps

1

Enter drinks consumed

Enter the number of standard drinks consumed. A standard US drink is about 12 oz of regular beer (5%), 5 oz of wine (12%), or 1.5 oz of distilled spirits (40%) — each contains roughly 14 g of pure alcohol.

2

Enter weight, unit, and biological sex

Enter body weight and choose lb or kg. Select biological sex, which is used only to set the Widmark distribution constant (r) for the BAC estimate.

3

Enter hours since your last drink

Enter how many hours have passed since the last drink. This is used to phrase where you likely sit within the detection window, not to recompute the window itself.

4

Read the Detection Window, BAC Estimate, and Caveats tabs

The Detection Window tab shows a general reference range, not a precise prediction. The BAC Estimate tab shows a supporting Widmark calculation. The Caveats tab lists the limitations you should understand before relying on either number.

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Reference

Formula & Methodology

2 formulas

Widmark BAC estimate

BAC (%) = (drinks × 14g ÷ (weight_kg × r × 1000)) × 100 − (0.015 × hours elapsed), floored at 0

1 US standard drink contains about 14 g of pure ethanol. The distribution ratio r is 0.73 for male and 0.66 for female (Watson-default values), matching this site's BAC Calculator. Alcohol is eliminated at roughly 0.015% BAC per hour.

EtG detection window (reference range)

Light (< 2 drinks): 12–24h (500 ng/mL) / 24–36h (100 ng/mL); Moderate (2–4 drinks): 24–48h / 48–60h; Heavy (> 4 drinks): 48–72h / 72–80h

The detection window is bucketed by how much was consumed, not derived from the BAC number. Two common lab cutoffs are shown: a standard 500 ng/mL cutoff typical of workplace/legal testing, and a more sensitive 100 ng/mL cutoff that detects alcohol for longer but is more prone to incidental-exposure false positives.

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YMYL

Trust, Methodology & Sources

Reviewed by Calculover Editorial Review · Updated 2026-07-23 · 2 sources

Editorial accountability

Author: Quinn Sumner - Editor

Owner: Quinn Sumner - Editorial owner

Reviewer: Calculover Editorial Review - Clinical-source review

Last reviewed: 2026-07-23

Last verified: 2026-07-23

Data effective: 2026-07-23

Methodology

The BAC estimate implements the simplified Widmark formula using the same Watson-default distribution ratios as this site's BAC Calculator (r = 0.73 male / 0.66 female), with 14 g of pure ethanol per standard drink and an elimination rate of 0.015% BAC per hour. The EtG detection-window reference ranges are sourced from SAMHSA's public advisory on EtG and EtS biomarkers and are bucketed by drinking pattern (light / moderate / heavy) at two common lab cutoffs (500 ng/mL and a more sensitive 100 ng/mL), presented as a population-level range rather than an individual prediction.

Assumption: Alcohol content follows the standard-drink convention: ~14 g (0.6 fl oz) of pure ethanol per standard drink.

Assumption: The Widmark distribution ratio uses fixed default values by biological sex (0.73 male / 0.66 female) rather than an individualized body-water calculation.

Assumption: The EtG detection window assumes no incidental non-beverage alcohol exposure and typical hepatic/renal function.

Assumption: Elimination is modeled at a constant 0.015% BAC per hour, without adjustment for food, medications, or individual metabolic variation.

Limitations & guidance

Individual metabolism, hydration, liver function, and body composition all affect actual BAC and EtG clearance, and none of these are modeled here.

Food intake and medications are not accounted for in the BAC estimate.

EtG detection windows are population-level reference ranges, not a prediction for any specific individual or specific lab assay.

Incidental alcohol exposure (mouthwash, hand sanitizer, cooking with alcohol) can cause a positive EtG result independent of beverage consumption, especially at sensitive cutoffs.

This tool cannot guarantee any outcome for an actual test and makes no representation about employment, legal, custody, or treatment-program consequences.

Professional guidance: This calculator provides a general educational reference range only. It is not medical or legal advice, and it does not predict the result of any specific EtG/EtS urine test. Actual detection depends on the testing lab's cutoff, individual metabolism, hydration, liver function, and other factors this tool cannot account for. Do not use this tool to make decisions about employment, legal proceedings, treatment programs, or any test you are required to pass — consult a qualified medical or legal professional.

Primary sources

SAMHSA. The Role of Biomarkers in the Treatment of Alcohol Use Disorders, 2012 Revision (SMA12-4686)

Simpson G. Medicolegal alcohol determination: Widmark revisited. Clin Chem. 1988;34(5):888-889

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Glossary

Key Terms Explained

6 terms

EtG (Ethyl Glucuronide) A direct, minor metabolite of ethanol produced by the liver. Because EtG persists in urine well after the parent alcohol and its intoxicating effects have cleared, it is used to detect alcohol consumption over a longer window than a breathalyzer or blood test.

EtS (Ethyl Sulfate) A related alcohol metabolite often tested alongside EtG. Reporting both EtG and EtS together helps labs distinguish genuine alcohol consumption from certain non-beverage exposure sources.

Widmark formula A long-established equation for estimating blood alcohol content (BAC) from the amount of alcohol consumed, body weight, a sex-based distribution ratio, and elapsed time. It is an estimation method, not a measurement.

Distribution ratio (r) A Widmark-formula constant representing the fraction of body weight through which alcohol distributes (total body water proportion). Commonly approximated as 0.73 for men and 0.66 for women, though it varies by individual body composition.

Standard drink A reference unit of alcohol containing about 14 g (0.6 fl oz) of pure ethanol — roughly 12 oz of regular beer, 5 oz of wine, or 1.5 oz of 80-proof spirits.

ng/mL cutoff The concentration threshold a lab uses to call an EtG test result positive. A common cutoff is 500 ng/mL; more sensitive assays use cutoffs as low as 100 ng/mL, which detect smaller amounts of EtG (extending the detection window) but also increase susceptibility to incidental-exposure false positives.

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Scenarios

Real-World Examples

3 worked examples

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Light, early-evening drinker

Light use — 1 drink, 160 lb male, 6 hours elapsed

Drinks 1 Weight 160 lb Sex Male Hours elapsed 6

One standard drink falls in the light-use tier (fewer than 2 standard drinks). The estimated BAC is already low given 6 hours of elimination at ~0.015%/hour. The EtG detection window reference is roughly 12–24 hours at a standard 500 ng/mL cutoff, so at 6 hours elapsed this person is still within the typical window.

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Moderate social drinker

Moderate use — 4 drinks, 140 lb female, 3 hours elapsed

Drinks 4 Weight 140 lb Sex Female Hours elapsed 3

With 4 standard drinks at 140 lb (female r = 0.66), the Widmark estimate puts BAC in roughly the 0.06% range after 3 hours of elimination. This falls in the moderate-use tier, with an EtG reference window of roughly 24–48 hours at a standard cutoff.

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Heavy drinking episode

Heavy use — 8 drinks, 180 lb male, 12 hours elapsed

Drinks 8 Weight 180 lb Sex Male Hours elapsed 12

8 standard drinks places this in the heavy-use tier. Even after 12 hours of elimination the Widmark BAC estimate may still be measurably above zero, and the EtG reference window runs roughly 48–72 hours at a standard cutoff (up to ~72–80 hours at a more sensitive cutoff) — meaning this person is likely still well within the typical detection window.

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Deep Dive

Understanding the EtG Alcohol Detection Calculator

3 chapters · 4 min read

EtG (ethyl glucuronide) urine testing can detect alcohol consumption long after the alcohol itself has cleared the bloodstream, which is why it's used in workplace, legal, probation, and treatment-program settings. This calculator gives a general reference range for how long EtG might remain detectable, plus a supporting Widmark BAC estimate — both are educational approximations, not precise predictions of any specific test result.

How the detection window and BAC estimate work

The Widmark BAC estimate uses the number of standard drinks consumed, body weight, biological sex (via the distribution ratio r), and hours elapsed to approximate blood alcohol content: grams of alcohol consumed are divided by body weight and the distribution ratio, then converted to a percentage, with roughly 0.015% subtracted per hour for elimination.

The EtG detection window is a separate reference derived from published ranges tied to how much alcohol was consumed, bucketed into light, moderate, and heavy drinking patterns. It is not calculated arithmetically from the BAC number — the two are related in concept (more alcohol consumed generally means both a higher BAC and a longer EtG window) but are sourced and computed independently.

Why the detection window is a range, not a single number

EtG detection windows vary by lab testing cutoff. A common cutoff of 500 ng/mL is typical in workplace and legal testing; a more sensitive 100 ng/mL cutoff detects smaller amounts of EtG and therefore extends the window, sometimes by another day or more. Because this calculator has no way of knowing which cutoff a specific test uses, it shows both.

Individual factors — metabolism, hydration, liver function, body composition, food intake, and medications — all affect actual clearance time and are not modeled here. That is why the result is presented as a population-level reference range rather than a personalized prediction.

Limits and how this tool should be used

This calculator cannot tell you whether you will pass or fail any specific EtG test. Incidental alcohol exposure — mouthwash, hand sanitizer, cooking with alcohol, and some over-the-counter products — can produce a positive result, particularly at sensitive cutoffs, independent of any beverage alcohol consumed.

This tool is for general education only. It is not medical or legal advice, and it makes no representation about employment, legal, custody, or treatment-program outcomes. If a real test result matters to your situation, consult a qualified medical or legal professional.

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Questions

Frequently Asked Questions

6 questions

What is an EtG test and what does it detect?+

An EtG (ethyl glucuronide) test is a urine test that detects a direct metabolite of alcohol, ethyl glucuronide, along with a related metabolite EtS (ethyl sulfate). Unlike a breathalyzer or blood alcohol test, EtG can detect alcohol use well after the alcohol itself and its intoxicating effects are gone.

How long can EtG be detected after drinking?+

It depends heavily on how much was consumed and the lab's cutoff. At a common 500 ng/mL cutoff, EtG is typically detectable for roughly 12 to 72 hours depending on the amount consumed. At more sensitive cutoffs (e.g. 100 ng/mL), detection windows can extend up to about 80 hours or, in some research settings, even longer.

Why do different labs report different detection windows?+

Labs use different cutoff concentrations (commonly 500 ng/mL or a more sensitive 100 ng/mL) to decide what counts as a positive result. Lower cutoffs detect smaller amounts of EtG and therefore extend the detection window, but also increase the chance of a positive result from incidental, non-beverage alcohol exposure.

Can incidental alcohol exposure cause a positive EtG test?+

Yes. Mouthwash, hand sanitizer, certain cooking preparations, and other everyday products containing alcohol can produce a low-level positive EtG result, particularly at sensitive cutoffs. This is a well-documented limitation of EtG testing.

How accurate is the Widmark BAC estimate here?+

The Widmark formula is a well-established estimation method, but it is still an estimate. Individual metabolism, food intake, medications, hydration, and liver function all affect actual blood alcohol content, so the number shown here should be treated as a rough approximation, not a precise measurement.

Is this calculator medical or legal advice?+

No. This calculator provides a general educational reference range only. It does not predict the result of any specific EtG/EtS urine test, and it is not medical or legal advice. Do not use it to make decisions about employment, legal proceedings, treatment programs, or any test you are required to pass — consult a qualified professional instead.

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EtG Alcohol Detection Calculator

Your Situation

Estimated EtG Detection Window

Widmark BAC Estimate

Important Limitations

How to Use This Calculator

Enter drinks consumed

Enter weight, unit, and biological sex

Enter hours since your last drink

Read the Detection Window, BAC Estimate, and Caveats tabs

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Light, early-evening drinker

Moderate social drinker

Heavy drinking episode

Understanding the EtG Alcohol Detection Calculator

How the detection window and BAC estimate work

Why the detection window is a range, not a single number

Limits and how this tool should be used

Frequently Asked Questions

Get a branded PDF of your results

EtG Alcohol Detection Calculator

Your Situation

Estimated EtG Detection Window

Widmark BAC Estimate

Important Limitations

How to Use This Calculator

Enter drinks consumed

Enter weight, unit, and biological sex

Enter hours since your last drink

Read the Detection Window, BAC Estimate, and Caveats tabs

Formula & Methodology

Trust, Methodology & Sources

Key Terms Explained

Real-World Examples

Understanding the EtG Alcohol Detection Calculator

How the detection window and BAC estimate work

Why the detection window is a range, not a single number

Limits and how this tool should be used

Frequently Asked Questions

Get a branded PDF of your results

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