Short answer
No fixed number. The THC detection window depends on test type, use pattern, dose, body fat, metabolism, hydration, and product potency. A urine test can detect THC for 3 days after one use and 30 days or more after regular use. Blood and saliva windows are shorter. Hair tests look back about 90 days.
Test type sets the range
Urine tests measure THC metabolites. A common urine screen cutoff is 50 ng/mL. A common confirmation cutoff is 15 ng/mL. Blood tests measure parent THC and metabolites. Blood detection can last 1 to 2 days. Saliva tests can detect THC for 24 to 48 hours. Hair tests can detect metabolites for up to 90 days.
Use pattern and dose
Regular use builds a metabolite load. A single low dose can clear in 3 days. Regular high dose use can last 30 days or more. Regular use and high potency products raise the load. A long detection window does not mean the drug still causes impairment.
Body fat and metabolism
THC is fat soluble. Fat stores release metabolites over time. Higher body fat can extend the urine window. Metabolism rate changes clearance. Age, liver function, genetics, and other drugs can change metabolism.
thc detection times in blood urine hair
Hydration and sample timing
Water intake changes urine concentration. Dilute urine can lower metabolite concentration. This can push a result below the cutoff and shorten the measured window. First urine of day is more concentrated. Sample timing after use matters.
Product potency and route
Higher THC dose gives more metabolites. Concentrates, edibles, and tinctures can deliver large doses. Route changes peak time and detection. Edibles delay peak. Inhaled THC peaks in minutes.
Individual factors and cutoff
Body weight, sex, kidney function, and drug interactions may change clearance. Lab cutoff changes result. No formula predicts one person's window. A test near a cutoff can pass one day and fail the next.
What the window does not show
Detection does not equal impairment. THC can stay in urine after effects end. Blood THC links to recent use but not a fixed impairment level. Use test results with time of use and observed behavior.