I am kind of interested in this question myself, seeing as I am holding onto about 10x 50 mg Tramadols. I have no actual experience taking Tramadol except one time I was on the first day off dope and on Suboxone, I was still hurting bad even with the Subs so I took 100 mg (all I had) and it didn't do much. But I was sick as a dog, the Sub was barely providing any relief, so its no surprise measley 100 mg of Tramies didn't help either.
To answer the question, it is supposedly around 20 and 15 mg respectively. Also tramadol is 1/10th the strength of morphine, so 30 mg morphine. That is going off an equianalgesic chart. I don't know if the euphoria from tramadol can match that of oxycodone, even a pretty light dose like 15 mg.