Minecraft wiki entry for The_Nether, associated text: Locations in the Nether correlate to Overworld coordinates, but horizontal Overworld distances are scaled down by a ratio of 8:1 for travel in the Nether. Therefore, traveling one block in the Nether means traveling eight blocks in the Overworld. For example, in a perfect scenario, a player who enters a portal in the Overworld at x=0, z=0 and travels in the Nether to x=1000, z=1000 returns to the Overworld at x=8000, z=8000. This makes portals a useful tool for traveling long distances in the Overworld.