If it's the Spektrum full range systems it's huge, I assume that you are looking for usage outside of RC jets? If you want actual numbers I suggest you contact Horizon, most modelers buy radio's knowing that the range is far more than what we will use but don't know any actual numbers.
But keep in mind, Spektrum also has some park flier systems (don't remember which ones) and they have a much shorter range (this may have also changed by now, but I haven't bothered to keep up with the lower channel systems at all).
Simple answer though, call Horizon and ask, or email them.