How to Link Nether Portals (Fast Travel)

Guide Java Bedrock

Quick answer: The Nether is 1:8 with the Overworld: divide your Overworld X and Z by 8, build a portal at those Nether coordinates and light it - the two portals link. In Java, the game searches 128 blocks in the Overworld and 16 in the Nether for an existing portal before creating a new one.

What you need

10 obsidian per portal (14 for the full frame) + flint and steel
Your Overworld coordinates (F3)
Safe paths in the Nether for the hub

Step by step

The rule: 1 block in the Nether equals 8 in the Overworld (X and Z only - Y stays the same).
Stand at your Overworld base, note X and Z (F3), divide both by 8 rounding down. That is where the matching portal goes in the Nether.
Build and light the Nether portal at exactly those coordinates. Walk through and back - the portals now link both ways.
Why portals mis-link: when you enter a portal, the game converts your position and looks for an existing portal nearby - 128 blocks radius in the Overworld and 16 in the Nether on Java (128 in both on Bedrock) - before generating a new one.
Fixing a mis-link: break the wrongly placed portal, rebuild it at the exact divided coordinates and relight. Also check the Y: the game picks the nearest portal counting height too.
Build a Nether hub: portals for each base connected by safe tunnels or blue-ice boat roads - travel is 8x faster than the Overworld.
Long distances beyond the world edge behave differently near X/Z 30 million - normal bases never hit that.

Java vs Bedrock

Java and Bedrock use the same 1:8 conversion; only the portal search radius differs (16 vs 128 blocks in the Nether).

Versions: The 1:8 ratio has never changed. Search radii: Java 128 Overworld / 16 Nether; Bedrock 128 in both dimensions.

Frequently asked questions

My portal took me somewhere random - why?

No portal existed within search range of your converted coordinates, so the game generated one in the nearest valid spot. Build your portal exactly at X/8, Z/8 (same Y) to force the link.

How far must two Overworld portals be to not collide?

On Java, Overworld portals within 1024 blocks of each other share the same Nether portal zone (128 Overworld blocks = 16 Nether blocks). Space Nether portals at least 16 Nether blocks apart.