THC Breakdown Calculator
How long is THC detectable?
How long THC can be detected in the body varies considerably depending on the test method, frequency of use and individual factors. A single use of cannabis can usually only be detected in the blood for a few hours, but in urine for several days. With regular or daily use, the detection time becomes much longer, because THC is stored in fatty tissue and slowly returns to the blood.
Five short questions lead to a personalised estimate with a specific date from which THC is expected to be no longer detectable, exportable as a calendar entry.
Question 1 of 5
Frequency of use
Which test methods detect THC?
Four test methods are used most often in practice, each with a different detection time and a different area of application.
Blood test
A blood test detects active THC and its main metabolite 11-OH-THC. These values are relevant for assessing fitness to drive. Active THC indicates recent use: usually only a few hours after a single intake, up to several days with regular use.
Urine test
A urine test detects the breakdown product THC-COOH. Because THC-COOH is excreted much more slowly than active THC, the urine test has the longest detection time of the standard methods: up to eight weeks with very frequent use. Rapid urine tests are the most common method for routine checks at work.
Saliva test
The saliva test detects active THC via the oral mucosa and is mainly suitable for detecting very recent use. The detection time is a few hours after single use and up to four days with regular use. Police traffic checks often use saliva tests because they are quick and non-invasive.
Hair analysis
A hair analysis detects cannabis use retrospectively for about 90 days per centimetre of hair length. Because the test covers very long periods, it is usually only used for examinations ordered by the authorities, such as the German Medical-Psychological Assessment (MPU).
Which factors influence THC detection time?
THC, the psychoactive substance in cannabis, is broken down in the body at different rates. Four main factors determine the individual detection time:
Frequency of use
After single use, THC disappears from the blood relatively quickly. With regular or daily use, THC accumulates in fatty tissue, which makes the detection time much longer.
Route of intake
With inhalation, THC reaches the bloodstream within a few minutes and is metabolised relatively quickly. With oral intake, first-pass metabolism takes place in the liver. As a result, the metabolite THC-COOH remains detectable for longer.
Body weight and body fat percentage
THC is fat-soluble and is stored in fatty tissue. People with a higher body fat percentage tend to show longer detection times, because THC returns more slowly from the fat stores to the blood, where it is metabolised.
Metabolism and individual factors
Metabolic rate, fluid intake, physical activity and liver function influence how quickly THC is excreted. A calculator cannot reflect these individual factors. The values should therefore always be understood as an estimated range.
Detection times at a glance
THC limits for driving in Switzerland
In Switzerland, there is effectively zero tolerance: from a THC level of 1.5 nanograms per millilitre of blood (1.5 ng/ml), a person is considered unfit to drive. This limit is considerably stricter than in many neighbouring countries. In Germany, the limit in force since 2024 is 3.5 ng/ml.
Anyone who uses cannabis regularly and drives should allow generous waiting periods, because the individual breakdown time can differ considerably from the average values. Repeated offences in Switzerland can lead to withdrawal of the driving licence, high fines and a traffic medicine assessment.
Can THC breakdown be accelerated?
THC is fat-soluble, is metabolised by the liver and excreted via stool and urine. The natural breakdown cannot be accelerated to any significant extent. The metabolism works at its own pace. What can support it:
Helpful
Drinking enough fluids, two to three litres of water a day, regular physical activity such as endurance sport, a high-fibre diet, enough sleep and abstaining from further use support the natural breakdown.
Ineffective or counterproductive
Detox drinks and detox programmes from the internet are not scientifically proven. Some detox products can even be assessed as an attempt at manipulation in modern tests. Sauna sessions and excessive exercise immediately before a test can even raise the values in the short term, because THC is released from fatty tissue into the blood.
Swiss hemp products with <1% THC
Green Passion carries a wide range of Swiss hemp products. Product categories at a glance:
Frequently asked questions
Sources and further information
- Deutsche Gesellschaft für Verkehrsmedizin (DGVM): statement on the waiting time after THC intake
- Allgemeiner Deutscher Automobil-Club (ADAC): information on THC detectability in road traffic
- Federal Office of Public Health (FOPH, Switzerland): cannabis and road safety
- Traffic Regulations Ordinance (VRV, Switzerland), Annex 8: substance limits
- Peer-reviewed studies on cannabis pharmacokinetics (Huestis et al., Karschner et al.)
