Calculations indicated that a return trip to the Milky Way from Triangulum, using maximum warp speed, would take over three hundred years. A subspace radio message, sent from the Triangulum Galaxy to Starfleet Command, was estimated to have a travel time of fifty-one years set to arrive in the year 2415. (TNG: "Where No One Has Gone Before")
With a return trip time of three hundred years using maximum warp speed, Federation technology had matched that seen of the Kelvan Empire in TOS: "By Any Other Name". The Kelvans made a voyage from the Andromeda Galaxy to the Milky Way in three centuries, remarked at in amazement by James T. Kirk who stated that, in the 23rd century, it would have taken a starship "thousands of years" to travel between galaxies.