...would be nice to display the speed in warp factors though (as an alternative) ;-)
Just looked up the star trek wiki for some figures! Warp 1 is of course 1.0c, from there on in the Original Star trek with kirk (and enterprise if you like the scott bakula show) Vc increases to the cube of the warp factor!
all figures are rounded
Warp 2 = 8c
Warp 3 = 27c I find this to be just above a common super cruise speed in system.
Warp 3.6 = 46.7c pretty good for looking around for planets in outer systems
Warp 4 = 64c
Warp 5 = 125c
Warp 7 = 343c I can reach this easily when cruising through large systems
Warp 10 = 1000c
Warp 12 = 1728c The top speed of the enterprise around the original movies*
Warp 12.3 = 1861c the fastest I have ever gone^1
Warp 12.6 = 2000c possibly a game limit, read it somewhere, but i'm not sure of the source.
^1 was exploring in a system with no scoopable stars, and forgot to keep track of time, so i decided to experiment by trying to close the distance and reduce mass in super cruise, in order to try and be able to jump to the nearest system. didn't work
but i got about 6,000,000 Ls out (0.19 Ly, no it doesn't change over to light years, change that please FDEV! Consistent scalable units!)
for TNG and newer style warp speed (goes to infinity the closer you get to warp 10):
Warp 2 = 10c
Warp 2.7 = 27.4c in system speed
Warp 3.2 = 48.3c looking for outer planets
Warp 4 = 102c
Warp 5 = 214c
Warp 5.8 = 351c
Warp 8 = 1024c
Warp 9.36 = 1728c (original Enterprise in new scale)
Warp 9.6 = 1880c Enterprise-D max speed for 12 hours
Warp 9.78 = 2000c
Warp 9.975= 3053c Voyager max speed
