I asked a similar question, and the answer or at least understanding I received was that for the most part, spacial distances are somewhat arbitrary, and that it's not really possible to calculate the distance between two points in hyperspace.
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Warning this is strictly Orions McPhees Opinion, it may or may not have any bearing on events true or imagined
The equation used to calculate your hyperspace travel time is secret. Not sure about the one used to calculate intra-system travel, but I think that one is secret as well.