Nether Portal Calculator

How the Nether Portal Calculator works

The Nether is a shortcut. Every block you walk there covers eight blocks of Overworld, so a 1,000 block trip becomes 125. That only works if your portals are paired correctly. Build one in the wrong place and the game either creates a new portal somewhere awkward, such as over lava, or links you to the wrong one.

How the Nether portal calculator works

Horizontal coordinates scale by 8. Going into the Nether, X and Z are divided by 8 and rounded down. Coming out, they are multiplied by 8. Y is never scaled, so a portal at Y 70 maps to Y 70.

The formula is Nether = ⌊Overworld ÷ 8⌋ for X and Z, and Overworld = Nether × 8 on the way back.

Overworld X or Z and the matching Nether X or Z, rounded down

Worked examples

Example 1: an Overworld portal at X −1,234, Y 64, Z 567. Dividing by 8 gives −154.25 and 70.875, which round down to X −155, Z 70. Build the Nether portal there at Y 64.

Example 2: a Nether portal at X −40, Y 40, Z 95. Multiplying by 8 gives X −320, Z 760 in the Overworld, still at Y 40. How many blocks does that save? The base is 825 blocks from 0, 0 in the Overworld but only 103 in the Nether.

Rounding down matters for negative numbers. −1,234 ÷ 8 is −154.25, which rounds down to −155, not −154. Getting the sign wrong is one of the most common reasons portals fail to link.

How portals pick a partner

When you step through a portal, the game converts your position and searches for an existing portal near that spot. In Java Edition the search covers 16 blocks around the target in the Nether, or 128 blocks around it in the Overworld. Because 16 Nether blocks equal 128 Overworld blocks, the two radii cover the same ground. If a portal is found, you arrive at the nearest one. If not, the game builds a new one as close as it can.

That is why two Overworld portals placed fewer than about 128 blocks apart can end up sharing one Nether portal. Give each Overworld portal its own Nether partner built at the exact converted coordinates, and keep the Nether ends more than 16 blocks apart.

The Nether roof and Y level

The Nether is 128 blocks tall with a bedrock roof. Portal frames placed above Y 122 do not have room, and players who build on the roof can confuse the linking. Build your Nether portals at a sensible height, matching the Overworld Y as closely as the terrain allows. The calculator warns you if the Y you enter would land in the roof.

Planning a Nether hub

Many servers build a hub at Nether 0, 0 with ice-boat or tunnel highways running out along the axes. Convert each Overworld base to Nether coordinates first, then run a tunnel from the hub to that point. A base 4,000 blocks out needs only 500 blocks of tunnel, and the trip by ice boat takes well under a minute.

Tips and pitfalls

Use the block coordinates. Read the "Block" line on the F3 screen, or turn on coordinates in Bedrock settings, and stand inside the portal frame when you check.

Build the Nether side by hand. Light the Overworld portal, walk through, then tunnel to the calculated spot and build the proper partner there. Break the one the game made for you if it is not in the right place.

Check the table. It lists positions 8 and 16 blocks away from yours, so you can see which nearby spots map to the same Nether block and plan a hub of several portals.

Bedrock search distance differs slightly. Bedrock uses a similar search but is less precise about the nearest portal, so build to the exact coordinates there too.

How to read the result

The first line is where to build the portal on the other side. The Y line shows whether the height carries over or needs lowering. The search radius tells you how far the game will look for a partner, and the distance line shows how much walking the Nether saves.

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