THC Detox Calculator

Your THC Detox Timeline: How Long Does Weed Stay in Your System?

Get a personalized THC detox timeline: how long THC stays detectable in your body and how long your endocannabinoid system takes to fully recover. Based on published clinical research.

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THC is fat-soluble — higher body fat stores more THC

THC detection windows by usage pattern

Typical detection windows from published toxicology ranges. Your personal window shifts with body fat, metabolism, dose, and consumption method — the calculator above personalizes these ranges.

Usage patternUrine TestBlood TestSaliva TestHair Test
Occasional (1-2x/month)2–4 days1–2 days0.5–1 days90 days
Moderate (1-2x/week)5–10 days2–4 days1–2 days90 days
Regular (3-5x/week)10–21 days3–7 days2–4 days90 days
Daily15–30 days5–7 days3–5 days90 days
Heavy daily (multiple times/day)30–90 days7–14 days5–7 days90 days

How THC-COOH levels decay over time

Illustrative decay of relative THC-COOH levels after quitting, by usage pattern. Heavier, longer use stores more metabolites in fat tissue, so the curve flattens — this is why detection windows differ so much.

100%50%0%015304560Days since last useRelative THC-COOH level
Occasional (1-2x/month)Regular (3-5x/week)Heavy daily (multiple times/day)

What each drug test actually measures

Urine Test

Urine tests detect THC-COOH, the fat-stored metabolite — not active THC. Standard screening cutoff is 50 ng/mL with a ~15 ng/mL confirmation. Because THC-COOH releases slowly from fat tissue, urine has the longest variable window: 2–4 days after occasional use, up to 30–90 days after heavy daily use.

Blood Test

Blood tests measure active THC in serum, so the window is short: roughly 1–2 days for occasional use and up to 7–14 days for heavy daily use, as stored THC re-enters the bloodstream. Blood values are what driving-limit laws refer to.

Saliva Test

Saliva tests detect recent use — typically up to 24 hours after occasional use and up to about a week with heavy daily use. They are common in roadside checks because they indicate recent consumption rather than past use.

Hair Test

Hair analysis looks back roughly 90 days regardless of usage pattern: THC metabolites are deposited in the hair shaft as it grows (~1 cm per month), and segment analysis can even map months of use. It cannot show intoxication, only past exposure.

How this calculator works

The estimate starts from published toxicology detection windows for your usage pattern (the table above) and adjusts them with multiplicative factors for body fat, metabolism, activity level, consumption method, age, weight, dose, and years of use. The output is a range, not a point value — individual variation is real, and no calculator can replace a lab test. This tool is educational and not medical or legal advice.

Detection also depends on the test's cutoff: urine screenings typically flag at 50 ng/mL THC-COOH with lab confirmation around 15 ng/mL — a stricter cutoff extends the effective window. Blood limits for driving are set in ng/mL of active THC in serum and vary by country.

The Science Behind Endocannabinoid System Recovery

When you use cannabis regularly, your body adapts by downregulating CB1 receptors — the primary targets of THC in the brain. This is why tolerance builds over time: your brain literally has fewer receptors responding to cannabinoids. Understanding this process is key to understanding recovery.

CB1 Receptor Upregulation

Research published in Molecular Psychiatry shows that CB1 receptor density begins recovering within 48 hours of abstinence. After 28 days, receptor availability in most brain regions returns to levels comparable to non-users. For chronic heavy users, full normalization may take up to 90 days. This recovery follows a predictable exponential curve — fast initial gains that gradually plateau.

Dopamine System Normalization

Chronic cannabis use blunts the dopamine system, particularly in the striatum. Studies using PET imaging demonstrate that dopamine release capacity is reduced in daily users. After cessation, dopamine signaling gradually normalizes over 4-6 weeks, which explains why motivation, pleasure, and drive often feel flat during early recovery before improving substantially.

Sleep Architecture Recovery

Cannabis suppresses REM sleep, which is critical for emotional processing and memory consolidation. When you quit, you may experience vivid dreams or nightmares as your brain rebounds with increased REM activity. Sleep architecture typically normalizes within 2-3 weeks, though some users report disrupted sleep for up to 45 days.

Cognitive Function Restoration

Working memory, attention, and executive function are all affected by chronic cannabis use. Meta-analyses show that most cognitive deficits resolve within 72 hours to 4 weeks of abstinence. However, heavy users who started young may experience longer recovery periods for complex executive functions.

The endocannabinoid system is remarkably resilient. While the first 2-4 weeks are the most challenging, the brain's natural cannabinoid signaling fully restores itself with sustained abstinence — a process you can track day by day with the Klar app.

Frequently Asked Questions

How long does THC stay in urine?+
For occasional users, THC metabolites are typically detectable in urine for 3-4 days. Regular users may test positive for 15-30 days, while heavy daily users can test positive for 30-90+ days. THC-COOH, the primary metabolite tested, is stored in fat cells and released slowly over time.
Does body fat affect how long THC stays in your system?+
Yes, significantly. THC is lipophilic (fat-soluble), meaning it's stored in fat tissue. People with higher body fat percentages tend to retain THC metabolites longer. Exercise can temporarily increase blood THC levels as fat cells release stored THC, which is why some experts recommend avoiding intense exercise right before a drug test.
How long does the endocannabinoid system take to recover?+
Research shows CB1 receptor density begins recovering within 48 hours of abstinence. Most recovery occurs in the first 28 days, with receptors reaching near-normal levels. Full endocannabinoid system recovery, including dopamine normalization and cognitive restoration, typically takes 60-90 days for chronic users — which is why Klar focuses on the 90-day brain reset.
Can you speed up THC detox?+
While no method can instantly clear THC from your system, staying hydrated, exercising regularly, and maintaining a healthy diet can support your body's natural metabolic processes. Detox drinks and supplements have limited scientific evidence supporting their effectiveness. The most reliable method is simply time and abstinence.
Why do I feel worse before I feel better after quitting cannabis?+
This is due to your endocannabinoid system recalibrating. When you stop providing external cannabinoids (THC), your downregulated CB1 receptors haven't yet recovered, creating a temporary deficit. This manifests as withdrawal symptoms: irritability, insomnia, reduced appetite, and anxiety. As receptors upregulate over 2-4 weeks, these symptoms progressively resolve.
Is the endocannabinoid system recovery timeline the same for everyone?+
No. Recovery speed depends on several factors: duration and frequency of use, potency of products consumed, individual metabolism, body composition, genetics, and overall health. Our calculator provides personalized estimates based on the most significant variables, but individual experiences may vary.
Can you speed up THC metabolism to pass a drug test?+
Not meaningfully. THC metabolites (THC-COOH) are stored in fat tissue and released slowly, and no drink, supplement, or detox product has been clinically shown to change that clearance rate. Intense exercise can even release stored metabolites temporarily. The only reliable factor is time without cannabis — which is exactly what this calculator estimates.
Is 30 days enough to get THC out of your system?+
It depends on your usage pattern. After occasional or moderate use, 30 days is almost always enough for a urine test. With daily or heavy daily use, urine detection can extend to 60–90 days because THC-COOH accumulates in fat tissue. Hair tests look back roughly 90 days regardless of pattern.
How long do edibles stay in your system?+
Slightly longer than smoked cannabis at the same dose. Edibles pass through the liver first (first-pass metabolism), producing 11-OH-THC and prolonging metabolite presence — the calculator applies roughly a 15% longer window for edibles. Detection medium matters more than method: urine still dominates for lookback, and hair covers ~90 days either way.

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Medical Disclaimer This calculator provides estimates based on published research and should not be used as medical advice. Individual results vary significantly. Detection windows are approximate and should not be relied upon for legal or employment decisions. Always consult a healthcare professional for personalized guidance.