How Long Does Weed Stay in Your System? THC Detection Times

By the StartDrugRehab.com editorial team · Updated November 5, 2026 · Editorial policy

Quick answer

THC from weed shows up in urine for about 1–3 days after one use, 3–7 days with use a few times a week, 10–15 days with daily use and 30 days or more with heavy long-term use. Saliva tests cover about 1–3 days, and hair up to about 90 days.

Free detection-time checker

How long will it show up on a drug test?

Pick a substance, test type and how often it was used. Estimates are based on published research.

1 Substance

2 Type of test

3 How often

Usually detectable in urine · Weed / THC · once

About 1–3 days

What the test looks for: THC-COOH, an inactive metabolite of THC (urine); THC itself (blood, saliva)
On standard drug tests?: Yes — on standard 5-panel, 10-panel and federal workplace tests (50 ng/mL screening cutoff).
How fast it clears: THC is stored in body fat and released slowly, which is why frequent use is detectable for weeks.

Estimates, not a guarantee. Dose, how often and how long someone has used, body fat, hydration, metabolism and the lab’s cutoff all change the window. No calculator can tell you how a specific test will come out.

Worried about your use or someone else’s? Talk to someone 24/7: ☎ (833) 589-6933 Who answers?

How long does weed stay in your urine?

How long marijuana shows up depends far more on how often someone uses it than on how much they used last time. Urine tests look for THC-COOH, an inactive metabolite that builds up with frequent use.

Marijuana (THC) detection times by test type
Test	Once	A few times a week	Daily	Heavy daily, long-term
Urine	About 1–3 days	About 3–7 days	About 10–15 days	30 days or more
Blood	A few hours, up to about 1 day	Up to about 1–2 days	Several days, up to a week or more	A week or more — sometimes weeks
Saliva	Up to about 24–30 hours	Up to about 1–2 days	Up to about 3 days	Up to about 3 days
Hair	Often not detected	Up to about 90 days	Up to about 90 days	Up to about 90 days

These ranges come from clinical drug-testing guides. Very heavy users can go longer: in one study of chronic heavy users, urine tests stayed positive for an average of 27 days and up to 46 days in a row, with rare cases longer still. Some heavy users also flip between negative and positive results for a while after stopping.

Why THC stays in your system so long

THC is fat-soluble. It is stored in fat tissue and released back into the blood slowly over days or weeks, where it is turned into THC-COOH and passed in urine. The more often someone uses, the more is stored, and the longer it takes to clear. That is why a daily user and a one-time user can have such different results from the same test.

How long does THC stay in your blood and saliva?

In occasional users, THC is usually only in the blood for a few hours up to about a day. Daily users are different: THC has been found in the blood of some daily users for 7 days or more after they stopped, and in one study, low levels were still present in 2 of 5 chronic daily smokers after 30 days.

Saliva tests detect THC for about 24–30 hours after occasional use and up to about 3 days in heavy users. They are increasingly used for roadside and workplace testing because they reflect recent use.

Does weed show up in a hair test?

Hair tests can cover about 90 days, but they are less reliable for marijuana than for other drugs because THC does not bind well to hair. They are much more likely to detect frequent use than one-time use.

Does weed show up on a standard drug test?

Yes. THC is on nearly every drug panel, including 5-panel, 10-panel and federal workplace tests. The federal urine screening cutoff is 50 ng/mL, and some clinical labs use 20 ng/mL, which can detect use for longer. Secondhand smoke is very unlikely to cause a positive at standard cutoffs except under extreme conditions. Prescription dronabinol (Marinol) does test positive for THC.

Delta-8 THC and many CBD products can also lead to a positive result, since tests look for THC metabolites and many products contain or produce them.

What affects how long weed stays in your system?

How much and how often. A single use clears far faster than daily or heavy use, which can build up in the body.
The test and its cutoff. Every test has a cutoff level. Labs using lower cutoffs or more sensitive methods (like LC-MS/MS) can detect use for longer.
Metabolism, age and health. Liver and kidney function, age, genetics and other medications change how fast a drug is broken down.
Body fat and hydration. Fat-soluble drugs linger longer in people with more body fat. Diluted urine can lower concentrations, and labs check for dilution.

When a drug test is the least of your worries

If you are looking this up because you are worried about an upcoming test, it may be worth asking a bigger question: is your use starting to cost you something, such as your job, your health, money or relationships? Needing to plan around a drug test is itself a sign some people use to decide it is time for help.

Treatment is more flexible than most people expect. Outpatient programs let you keep working, and many plans cover rehab under federal parity rules. You can get matched with up to 3 programs in about a minute, browse rehab centers by state, or call the number on this page to talk it through. It is free and confidential.

Detection times for other substances

See every substance side by side on our drug detection times chart.

Frequently asked questions

How long does weed stay in your system after one use?

After a single use, THC is usually detectable in urine for about 1–3 days, in saliva for about a day and in blood for a few hours up to a day.

How long does THC stay in urine for daily users?

Daily use is usually detectable for about 10–15 days. Heavy, long-term daily use can be detectable for 30 days or more.

Can secondhand smoke make you fail a drug test?

It is very unlikely at standard cutoffs. Research has only produced positives from passive smoke under extreme conditions, such as hours in an unventilated room, and only at the lower 20 ng/mL cutoff.

Can CBD make you test positive for THC?

Yes, it can. Many CBD products contain small amounts of THC, and drug tests look for THC metabolites, not whether the product was legal.

Is marijuana addictive?

It can be. Cannabis use disorder is a recognized condition, and people who use daily can have withdrawal symptoms like irritability, poor sleep and low appetite when they stop. Outpatient treatment is often a good fit.