In something like Star Trek, you can say 'this ship can achieve Warp 6', which sets a specific limit on how fast that ship can go (depending on which warp scale you're using, which is a different matter). Does there exist a similar scale for Star Wars? Specifically, are there any limits or standards imposed on hyperspeed? I know the movies imply that anyone can travel anywhere instantaneously, whereas the EU tends to make journeys take days or even weeks. The only reference to hyperspace speed is Han's ".5 past lightspeed" which obviously doesn't make sense. Is the speed of hyperspace travel dependent entirely on the whims of the writer?
According to http://starwars.wikia.com/wiki/Hyperspace, this is kind of a loaded question.
Hyperspace is an "alternate dimension", which could only be reached by going to light-speed. However, once in hyperspace, the ship would travel through wrinkles in the fabric of real space to reduce journey time significantly.
So, by traveling 1.5 x the speed of light, Han made the Kessel Run in less than 12 parsecs...which might refer to he was able to travel at high enough speeds within Hyperspace, that he actually traveled between two points in space through Hyperspace, gathering up enough folds and wrinkles in hyperspace that the trip only took 12 parsecs
So... it's kind of like you're asking how fast can Jack O'Neill travel through the Stargate. Theoretically, according to the show, he could walk at 1 MPH and make it to the other side of the galaxy in a few seconds.