Everyone is different. Blood work is the only true way to know. I personally take .25 mgs ED with 200 mgs of test, or .4 mgs ED with 300 mgs of test. I have no gyno and if I take less than what I stated I start to get itchy nips and have had some puffyness form. When I used to use 750 mgs a week of test I had to take .75 mgs ED. I've heard guys on here that hardly need any and some need alot because their sensitive to test. I would start out with .25 ED or .5 EOD and go from there. Just have some Nolvadex on hand in case you start to develop gyno so you can stop it immediately while you adjust your AI dose. Just my 2 cents. Good luck.