Try roidcalc.com
"The Roid Calculator calculates the estimated blood level of different steroids, using half-lifes. The half-life is simply the time when 100 active milligrams breaks down to 50 active milligrams, to 25 active milligrams, and so on. The half-life may come after a few days, or a few hours, depending on the drug. You can use it to see how much 'roids' you really have in your blood. Please remember that the results are only approximate. The half-lifes used below is based on several scientific studies."
I've plugged in some numbers, but don't know exactly what I'm looking at. Interesting tho.