Read it on a board (can't remember the URL) and just from looking at the labs done by people who have done Test only, it's supposedly about 750-1000 ng per 100 mg of test per week. Also, if I recall there was a study comparing 300 mg and 600 mg of Test-E and at the end of the week the 600 mg group only had about 2300 ng/dl. I just think my test right now is waaay higher than I expect it or want it to be based on how much prop I am using.