This page will one day have assorted conversion functions you can use as a lookup. You know, for those times when you just gotta know the exact uplink frequency of GSM900 ARFCN 12. At the moment I am without all my reference material so even though I could write this put all this stuff in I would first like to verify things.
Anyway, as a sample and to test things will work satisfactorily Ive written a couple using Javascript and perl -> cgi.
They're made up don't forget...!