How Long Does THC Stay In Urine
without the guesswork.
Substance Detection Window Calculator — Interpret specimen, cutoff, confirmation and medical-review status without promising a drug-test pass date. Includes a practical guide and embedded calculator. Sensitive inputs stay in your browser.
A drug test is a specimen-specific measurement against a defined method and cutoff. SAMHSA guidance does not support converting a broad internet detection range into a guaranteed negative date.
Context matters.
- Do not use this page to time drug use, defeat a test or decide that driving, work, medication use or another safety-sensitive activity is safe.
- An initial non-negative screen may require confirmatory testing and review. A reported negative means the analyte was not reported at or above that test's cutoff; it is not proof of no exposure or no impairment.
- For a clinical result, discuss the exact laboratory report with the treating clinician. For a regulated workplace result, use the program's Medical Review Officer and challenge / retest process.
Sources & scope
This page shows the source trail, jurisdiction and review date alongside the result. Always confirm time-sensitive rules with the linked authority.
What to know before using the result.
Can this tool tell me the date I will pass a drug test?
No. A defensible interpretation requires the exact specimen, analyte, cutoff, collection procedure and confirmation method. CalcSpan intentionally does not generate a pass date.
Does a negative result prove there was no prior use?
No. It means the reported analyte was not detected at or above the method's cutoff in that specimen. Timing, specimen quality and the substances included in the panel still matter.
Is an initial non-negative result final?
Not necessarily. Workplace and clinical programs can require laboratory confirmation and medical review before a final interpretation, including review of legitimate medication context.