Nether Portal Calculator

How Nether coordinates work

The Nether is a smaller copy of the Overworld map. Each block you walk in the Nether covers 8 blocks in the Overworld on the X and Z axes. Height is not scaled, so Y stays the same. That gives four rules:

In Java Edition, press F3 to see your coordinates. In Bedrock Edition, turn on Show Coordinates in the world settings. X gets bigger as you go east, Z gets bigger as you go south, and Y is your height.

Rounding down, and why negative numbers trip people up

Most coordinates do not divide by 8 evenly. The game rounds down, to the lower whole number. For positive numbers that just drops the decimals: 805 ÷ 8 = 100.625, so the Nether block is 100. For negative numbers, rounding down moves away from zero. −5 ÷ 8 = −0.625, and the block is −1, not 0. A calculator that simply cuts off the decimals gets many negative coordinates one block wrong.

Show −5, 70, 12 near spawn

From the Nether back to the Overworld

Multiply by 8. One Nether block covers an 8 × 8 square of Overworld blocks, so a Nether X of 100 matches any Overworld X from 800 to 807. The calculator shows that range when you type on the Nether side. A fortress at Nether X −120, Z 340 sits under Overworld X −960, Z 2,720, which tells you where to build an Overworld portal that leads straight to it.

Show the fortress at −120, 70, 340

Dividing by 8 in your head

Dividing by 8 is the same as halving three times. 1,600 halves to 800, then 400, then 200. 3,000 goes to 1,500, 750 and 375. If a half lands on a decimal, finish the halving and round down at the end: 805 becomes 402.5, 201.25 and 100.625, so the Nether block is 100. For the trip back, double three times: 50 becomes 100, 200 and 400.

How to link two Nether portals

1. Build and light your Overworld portal. Stand in it and note X, Y and Z.
2. Type them into the Overworld panel. The Nether panel shows where the other portal belongs.
3. Go into the Nether through any portal and travel to those coordinates. With cheats on, the teleport command under the answer takes you straight there.
4. Build the Nether portal on that spot, close to the same height if the terrain allows, and light it.
5. Walk through in both directions. If either trip goes somewhere else, type the Nether portal's position into "Do your two portals link?" to see which side to move.

The first time you use a new portal, the game builds the Nether side for you. It lands near the right spot but not always on it, and sometimes on a ledge over lava. Building the Nether portal yourself at the converted coordinates gives you a clean link you can rely on.

Show a base at 800, 64, −1,600 with its Nether portal

Portal size and obsidian

A portal frame can be anything from 4 blocks wide and 5 tall up to 23 by 23, measured on the outside of the frame. The corners are optional, so a frame without them saves 4 obsidian. Portals the game builds for you always have their corners. Size does not change where a portal links.

How the game picks the portal you come out of

When you step into a portal, the game converts your position to the other dimension. Then it looks for an existing portal in a square around that point, from the bottom of the world to the top. If it finds one or more, it sends you to the closest. If it finds none, it builds a new portal within 16 blocks of the point, wherever there is room.

How big that square is depends on the edition and on the direction you travel:

In Java, 16 Nether blocks equal 128 Overworld blocks, so both directions search the same patch of ground. Java used 128 blocks in the Nether too until version 1.16.2, which cut it to 16 to match the 1 : 8 scale. A lot of older guides still give the old number. That is where the advice to keep Nether portals 128 blocks (1,024 Overworld blocks) apart comes from. Current Java needs far less room. In Bedrock the 128-block search still applies.

"Closest" is measured in a straight line in three dimensions, so height counts. Say one Nether portal sits right above the target point but 40 blocks higher, and another is 20 blocks to the side at the same height. The game picks the second one, because 20 blocks is less than 40.

Why your Nether portal links to the wrong portal

• It is outside the search square. In Java the Nether portal has to be within 16 blocks of the converted point. If it is farther away, the game builds a new portal and you come out of that one.
• Another portal is closer. The game always takes the nearest portal, counting height. A portal you forgot about, or a friend's, can win.
• The heights are far apart. A portal directly above the target but high up loses to one off to the side at the right height.
• Two Overworld portals are too close together. Overworld portals 16 blocks apart convert to Nether spots only 2 blocks apart. That leaves no room for two separate Nether portals, so both end up sharing one.
• Only the return trip fails. A pair can link one way and not the other. Coming back, the game looks within 128 blocks of the Nether portal's position times 8, and it skips an Overworld portal outside that square.

The fix is nearly always the same. Break the wrong portal, rebuild it at the converted coordinates, and test both directions. The link checker in the calculator tells you which side to move. In the example below the Nether portal is 30 blocks off its target, so in Java neither direction links.

Check a pair that won't link in Java

The same pair acts differently in Bedrock. The wider search finds the Nether portal 30 blocks away, so the trip into the Nether works. The trip back still fails, because the Overworld portal is 240 blocks from the point the game converts back to.

Check the same pair in Bedrock

How much faster Nether travel is

Every block in the Nether counts as 8 in the Overworld, so any trip is 8 times shorter. Sprinting moves you about 5.6 blocks per second. A 4,000-block trip takes about 11 min 53 s on the surface and about 1 min 29 s through the Nether, plus the walk to each portal.

Distances are in blocks and times are for a straight line at a steady speed, rounded to the second. A boat goes about 40 blocks per second on ice or packed ice and about 72.7 on blue ice, which is why long Nether tunnels are often paved with ice.

Plan a trip from 800, −1,600 to 3,200, 2,400

Planning a Nether hub

A hub is a room in the Nether with tunnels running out to each of your bases. Convert each base's Overworld coordinates, dig a tunnel from the hub to each converted point, and build a portal at the end. Tunnels that run straight along the X or Z axis are the easiest to follow. Keep them at one height and wall them in to keep out lava and ghast fireballs. Use the trip box in the calculator to see how long each tunnel will be.

Y levels, the Nether roof and the world border

Y is never scaled, but the Nether is only 128 blocks tall. Its floor is bedrock up to Y 4 and its roof is bedrock from Y 123 to 127. An Overworld portal at Y 150 has no matching height under the Nether roof, and a deep Overworld portal at Y −20 would point into the floor. In those cases build the Nether side at a height you can use. The calculator warns you when your Y falls outside the Nether's open space.

The Overworld ends at the world border, 29,999,984 blocks from the center. A Nether portal beyond about 3,750,000 blocks would point past that border, so the game keeps you inside it. This is the one case where multiplying by 8 does not give you the real exit.

Sources

• Minecraft Wiki, Nether portal: the coordinate rules, rounding, search areas by edition and the 1.16.2 change.
• Minecraft Wiki, The Nether: the 1 : 8 scale, height, and the bedrock floor and roof.
• Minecraft Wiki, Sprinting: sprint speed of 5.612 blocks per second.
• Minecraft Wiki, Boat: boat speeds on ice, packed ice and blue ice.
• Minecraft Wiki, Commands/execute: the dimension names used in the teleport command.
• Minecraft Wiki, World border: where the Overworld ends.