I only need .5mg per 100mg shot of test. Take both same day. Keeps my e2 in range even on 750 a week test.....but on 500 a week sometimes I take less. 1mg arimidex per every 250mg shot. E2 stays a bit higher but I feel good.So usually I do .5mg every 100mg of test but dial it back a hair if I get less horny. That usually doesn't happen until like in the third or fourth month on a cycle.Here I was on 750 test a week taking 1.25mg arimidex with every 250mg shot. Felt great but on week 16 I feel just a tad less horny ...so I dialed back the arimidex to 1mg every 250mg shot of test. I still feel great and I'm sure my E2 is a bit higher but with me I just don't want my E2 to get above about 70. When my E2 gets about above 70 that's when I start to get some pretty bad sides.So 38-70 e2 is were I like mine.