[summadat]

If memory serves me right, Warp speeds are x^3 faster for each step. Warp 1 is 3x faster than light, Warp 2 is 27x faster, etc

[_ea1k]

It actually varies from series to series: https://en.wikipedia.org/wiki/Warp_drive#Warp_velocities

[liberte82]

Warp speeds in Star Trek are as fast as the plot of that particular episode demands.