There are many tools for this. To name a few.. http://www.iwebtool.com/pagerank_prediction http://www.rustybrick.com/pagerank-prediction.php http://www.pagerankprediction.com/ I would recommend using iwebtool.
man i don't get it, I have several pr3, couple pr4, and even a pr5 backlink, and my predicted page rank is pr0
Well then obviously the tools you are using don't work. One pr 5, even with 100 links on the page will give you a pr 4, as long as the linking page stays pr 5 and Google actually follows the link.
I was commenting earlier on PR here You cannot reliably predict it, since G changes the algo as they see fit
pagerankprediction.com Showing Every site Prediction PR0 Including GOogle.com Prediction PR0 hhehehehe