A quick answer: Marijuana is generally detectable in urine for 3–30 days (a single use ~3 days; daily or heavy use up to 30+ days). Blood, saliva, and hair have different windows — and several personal factors change the timeline. Here is what the science says, and how to confirm a result definitively. (Also searched as: weed, cannabis, pot.)
Marijuana detection windows
Typical detection windows by test type:
| Urine | 3–30 days (a single use ~3 days; daily or heavy use up to 30+ days) |
|---|---|
| Blood | 1–2 days (up to a week in heavy users) |
| Saliva | up to 24–72 hours |
| Hair | up to 90 days |
Marijuana is the most-detected substance in U.S. workplace testing — 4.5% urine positivity in the Quest Diagnostics 2025 Drug Testing Index, the highest of any drug.
Detection windows are general estimates and vary by dose, frequency of use, individual metabolism, body composition, hydration, and the test’s cutoff level. They are not guarantees or medical advice. Hair testing generally reflects roughly the prior 90 days for all substances.
What affects how long Marijuana stays in your system
THC is fat-soluble, so it lingers far longer in frequent users and people with higher body fat than in occasional users. In general, higher doses, more frequent use, slower metabolism, and higher cutoff sensitivity all lengthen how long a substance is detectable. There is no reliable way to "flush" a substance out faster than your body clears it.
Test for Marijuana
To confirm Marijuana definitively, use a lab-confirmed test. Order a private at-home drug test (a 10 panel panel covers Marijuana), or set up employer testing. Every LabX positive is confirmed by LC-MS/MS.
Order an at-home test → For employers