Can you explain how long can thc stay in your urine?

Can be a long time: Chronic smokers of cannabis/marijuana/thc can test positive long after their last use. The two main tests that will reveal evidence of use at this later time are hair sample and urine sample. The average time following last use for a urine test is often cited as 30 days, but can be much longer. Thc can be stored in fat cells and released at a later time giving a positive test long after last use.