|Marijuana is the most commonly used and tested for drug in the United States and other countries. The effects weed has on the user and detection time depend on its potency, which is associated with the amount of THC (Tetrahydrocannabinol) it contains.
When you ask the question "How much time does pot stay in the body?", you need to consider the fact that there's no simple answer to the question. THC can stay in the system for as long as 3-90 days after smoking or being ingested orally. There are plenty of factors determining for how much time drug toxins stay in the system, such as your general health, your body weight, metabolic conversion, fluid taken, the degree of exposure to the drug toxin, etc.
The speed at which weed leaves your body rests both on the speed of your metabolic process and on the half-life of THC. THC is estimated to have a half-life that varies from 1 to 10 days. It's impossible to find out what that half-life is, which means that it is very hard to use it to estimate how much time it will stay in your system.
The type of test done can also have an impact upon if or not weed is detected. While urine drug tests are the most common, they are also the least accurate. Pot can still be detected in a urine test up to a month after the last administration. If you smoke it occasionally, it will stay in your system for up to 10 days. If you smoke marijuana regularly, it will remain in your system for as long as 45 days, and if you smoke pot constantly, it can remain in the system for as long as 90 days.
Blood sample are a lot more accurate, though more pricey. Because THC is accumulated in the fat cells of the major organs, the chemical is slowly released over time into the blood stream, where it eventually passes through the liver, is cleansed, and then eliminated.
And finally, hair tests. Hair contains a record of everything your system has been through while that hair was growing. Yet, testing of hair is very expensive and seldom done by employers.