How do we calculate the escape velocity of galaxies? How do we calculate the escape velocity of galaxies?
Do we have to know the total mass?
What is the escape velocity for Milky Way?
In short, the escape velocity from the region we find ourselves in the milky way is 544 Km/s +- 10%.

This number, and an extensive explanation of how it was calculated can be found on a paper called The RAVE Survey: Constraining the Local Galactic Escape Speed

Also important to consider is the fact that we already are at aproximately 220 Km/s because of the sun's orbital velocity, so the actual value needed to get there from earth is much lower.