How This Tool Projects PEth Elimination
Enter a laboratory phosphatidylethanol (PEth) result in ng/mL. The slider applies a published-style half-life in the 4–10 day range (this page defaults to 7 days — the value in the calculator, not a 6-day default). Each half-life period halves the remaining estimate. The tool does not invent a PEth number from drink counts.
Understanding PEth Cutoff Levels
This calculator’s reference tiers match the on-page legend: under 8 ng/mL (abstinence-style), 8–19 ng/mL, 20–199 ng/mL, and 200 ng/mL and above. Guides on this site also discuss 20 / 50 / 200 ng/mL bands. Always use the cutoff printed on your lab report. Full band notes: PEth test cutoff levels explained.
Frequently Asked Questions
What does a PEth test calculator estimate?
A PEth test calculator projects a known phosphatidylethanol (PEth) blood level forward using a published half-life so you can see typical detection windows and reference ranges. It is educational, not a lab result.
What PEth cutoff levels are commonly cited?
Clinical literature often discusses about 20, 50, and 200 ng/mL as interpretation bands. CalcGrain shows those as reference tiers only — your lab’s cutoff is the one that counts.
How long does PEth stay positive?
Depends on starting level and drinking pattern; heavy chronic use produces longer positives than light exposure.
Can PEth detect a single binge?
It reflects recent weeks of exposure. One episode may contribute but interpretation depends on magnitude and timing.
Can a single drinking session raise PEth into a positive range?
It can contribute, but whether the result sits in a positive band depends on magnitude and timing. This page does not convert drinks into a PEth number; that interpretation belongs with a clinician.
What half-life should I use?
Literature suggests ~4–10 days; this tool defaults to 7 days. Your clinic may use a fixed assumption.
How long does a PEth blood test detect alcohol?
PEth generally reflects roughly 2–4 weeks of exposure, depending on starting level and drinking pattern — longer than typical urine ETG for one session.
What is a PEth abstinence cutoff?
Programs often cite single-digit ng/mL lines such as 8 or 20 ng/mL. Always use the cutoff on your lab report.
Can I estimate PEth from drink counts here?
This page projects a known PEth value forward. It does not convert standard drinks into a PEth number.
Why is PEth used instead of urine ETG?
Clinicians want a weeks-long picture of drinking rather than last weekend. The markers answer different questions.
How long does it typically take PEth to fall below a given cutoff?
In this model it is a half-life projection from the ng/mL you enter: each half-life period (default 7 days, range 4–10) halves the remaining value. Time to a cutoff such as 20 ng/mL or 8 ng/mL therefore depends on the starting lab number, not on a single calendar rule.
Can common non-alcohol products cause a false positive PEth result?
This projector does not model mouthwash, sanitizer, or other incidental products. Those incidental-ethanol questions are documented on this site for urinary EtG, not as a PEth interpretation from this tool. Use the cutoff printed on your blood-test report and ask the ordering clinician.