How large are the maps in the game?

[PongoBongo]

I keep seeing 4km2 and 16km2 listed, but how large are these maps compared to other games. How many blocks make a km? I'm having trouble visualizing the map size, any help would be appreciated.

[8Pfundspeck]

set a waypoint and walk away now u know how far a mile or kilometer is. done

[QC]

A world that is .52km2 (Default Size) has a diameter of 520 meters 1 meter per block, So logic dictates that a 4mk2 world would have a diameter of 4,000 blocks or 4,000meters. 16km2 respectively would be 16,000 blocks or 16,000 meters

[City Builder]

They're surprisingly small. I don't know the exact measurement but I can run around the circumference of the planet in no time at all. Most of my worlds that I've generated thus far have far more water than they do land which is what makes them feel really small to me.