Unfortunately, we do not have a definitive answer as to how long cannabis will stay in your system. There are a number of factors that contribute to how much THC is present in your body at any given time including how much body fat you have, how active your metabolism is, how often you consume cannabis and what you are consuming (flower, edibles, tinctures, concentrates). With that said, on average, it may take anywhere from 3-4 weeks for the body to get rid of THC in your system.
Check out this article of ours that provides more information on How to Flush Marijuana from Your Body.
I hope this information helps! :-)
It wasn't for a workplace test, but I have a few times while job hunting. I would stop cold turkey, and then take a test every week until it came back clean. One time it took 3 weeks, another time 4, and another time, nearly 5 weeks! I consume cannabis daily, and one thing to note, is that each of those times, my tolerance was higher than the time before, so each time, it took a little longer to come back clean when I would quit.
So, it's different for every one, and it will depend on your tolerance, usage, and length of usage, but at least here's a reference point to go off of.
I hope that helps!