THC Detection Calculator
Answer a few quick questions — get personalized results backed by science.
Trusted by 9,000+ people every month — helping you make sense of a stressful situation, with clear answers instead of guesswork.
Created together with
Dr. Matthew Nuesse, DOT Certified Medical Examiner.
Built on the science
Every estimate is based on peer-reviewed toxicology research, not guesswork.
Know what to do next
Get matched to the right test kit for your exact timeline, based on your result.
About this calculator
What it estimates: a personalized urine THC detection window at two thresholds — Standard (50 ng/mL, the common workplace cutoff) and Confirmatory (15 ng/mL, a more sensitive lab-grade cutoff).
What it's based on: peer-reviewed toxicology research, reviewed by Dr. Matthew Nuesse, DOT Certified Medical Examiner.
What it doesn't do: it doesn't estimate blood, saliva, or hair detection windows, and it isn't a substitute for an actual test — individual results vary based on physiology, hydration, and metabolism.
Why we ask what we ask: each question — age, body type, usage frequency, duration of use, and lifestyle factors — directly affects how quickly THC clears your system. More accurate answers give a more personalized estimate.
Read the full methodology →*Your answers are stored securely, never shared with third parties, and used only for research purposes.
⚠ Prolonged retention beyond this estimate has been documented in extreme chronic-use cases. Consider an at-home confirmatory test before relying on this range alone.
| Urine Test Cutoff | Estimated Window | Notes |
|---|
Estimates are based on peer-reviewed toxicology research and population averages (Huestis 2007; Goodwin et al. 2008; SAMHSA cutoff guidelines). Individual results vary by physiology, hydration, and metabolism. This tool is informational only and is not medical or legal advice.
50 ng/mL and 15 ng/mL are standard federal screening and confirmation cutoffs (49 CFR §40.85).
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