How big should my map be for a Survivor VS Zombie game?

How big (in studs) should my map be for a game where survivors are running away from zombies trying to survive? I was thinking 512x512 studs. Inside this 512x512 region will be buildings, forests, etc. Is 512x512 too small?

Pretty simple question, but I need help because I’ve never done this before.

I would go for 815 by 815 studs but it might be a bit big or go with 715 by 715. It is up to you but I guess 512 by 512 could work. Lastly, you should increases the studs if needed to expand your build but make sure the map is not too big.