The basics of how portals link to each other. Credit to figuring out the algorithm goes to pudquick: bit.ly/MCPortals

1. How Portals Work Eric Haines http://vokselia.com 5/30/2011

2. Overworldvs.Nether Coordinates Use F3 to find your coordinates. X is north/south (south is positive), Z is east/west (west is positive). Overworld to Nether: Nether X = OverworldX / 8 Nether Y = OverworldY (no change) Nether Z = OverworldZ / 8 So (386,116,-837) in the Overworld converts to (48.25,116,-104.625) Nether Nether to Overworld: Overworld X = Nether X * 8 Overworld Y = Nether Y (no change) Overworld Z = Nether Z * 8 So (46,95,-117) in the Nether converts to (368,95,-936) in the Overworld

3. Overworld Portal to Nether Convert the player’s location from Overworld to Nether coordinates. From the Nether X and Z (north/south, east/west) location, look in the Nether for 128 blocks north, south, east, and west. Find the closest Nether portal to the player’s location. Distance is measured in 3 dimensions. Steve pops into the Nether. The program searches for the closest portal in a box that’s 257x257 wide and 128 high (the world’s height) in the Nether. 128 high -128 +128

4. If no portal is inside this volume… Then a new portal is spawned close by, in an area large enough to hold it. Instead of spawning a portal at Steve’s location in solid rock, it is placed in a cave.

5. Overworld to Nether Range Searching from the Overworld into the Nether searches 128 meters in each direction in the Nether. This distance is the same as 1024 meters in the Overworld. A single portal in the Nether will be connected, one way, from any Overworld portal within the 1024 meters box around it. So, a box of size 2048x2048 (approx.) in the Overworld can connect to one Nether portal. 1024m 1024m 128m 128m

6. Nether Portal to Overworld Uses the same sort of process: find the player’s Nether location in the Overworld and then find the closest portal within a box 128 meters (blocks) north, south, east, and west of that location, in the Overworld. Note the key difference: 128 meters in the Overworld is just 16 meters in the Nether. So a Nether portal searches a much smaller box, 256x256 Overworld-equivalent vs. 2048x2048 Overworld-equivalent. Nether portals search a much smaller overall equivalent space! 128m 128m The left Overworld portal is in range, the right is not. 16m 16m

7. Conclusions To make an unbreakable two-way link between Overworld and Nether portals, build them at the exactly the same locations in each world. Going from an Overworld portal to a Nether portal can go a long distance and is very common, since the search range is huge in Overworld term. But, it’s often a one-way trip, since the Nether portal searches a relatively small range when looking in the Overworld for a nearby portal. This small search range also means that, if you build a portal in the Nether, it is pretty easy to (accidentally or on purpose) spawn a new portal in the Overworld. If your Nether portal’s Overworld location is more than 128 meters away, in a cardinal direction (north/south or east/west), from any Overworld portal, a new Overworld portal will be created.