What your result means
The big number is where to build the matching portal on the other side. Travelling one block in the Nether moves you eight blocks in the Overworld, so a Nether hub lets you cross huge distances quickly — and a portal pair only links reliably if both ends sit at the converted coordinates. Obsidian for the frame is the material cost of the portal itself, portal blocks inside is the purple area you walk through, and lava buckets is what it takes to cast that obsidian in place with a bucket of water if you have no diamond pickaxe.
The game reuses a nearby portal before it builds a new one
When you step through, Minecraft converts your coordinates, then searches around the arrival point for an existing portal. If it finds one it sends you there instead of creating a fresh portal — which is why two Overworld portals built close together often end up sharing a single Nether portal and dropping you in the wrong base.
The fix is spacing. Overworld portals more than 1,024 blocks apart convert to Nether points more than 128 blocks apart, comfortably outside the search area. Building the far-side portal yourself, at exactly the coordinates above, also pins the link because the game finds your portal first.
How it works
Horizontal coordinates are scaled by the fixed 8:1 ratio between the two dimensions: divide X and Z by 8 going into the Nether, multiply by 8 coming out. Height is never scaled — Y stays as it is, so a portal at Y 64 in the Overworld links to Y 64 in the Nether. The obsidian count is the frame perimeter: two runs along the top and bottom and two up the sides, with the four corners optional because the portal lights without them. Lava buckets equal the obsidian count, since each cast block needs one bucket of lava.
How to use this calculator
- Press F3 in game (or check your map) and read off the coordinates of the portal you already have.
- Pick the direction you are converting, then type X, Y and Z.
- Copy the teleport command if you are on a creative or admin world, or write the numbers down and travel there.
- Set the frame size you want — 4 × 5 is the cheapest, larger frames are cosmetic — and check the obsidian count before you mine.
- Build the far-side portal at those coordinates so the pair links to each other and nothing else.
Formula
Overworld X = Nether X × 8 Overworld Z = Nether Z × 8
Y is unchanged
Obsidian = 2(W − 2) + 2(H − 2)
X and Z are the horizontal coordinates and Y is height. W and H are the outside width and height of the portal frame in blocks, so the purple portal area inside is (W − 2) × (H − 2). Add 4 to the obsidian total if you want the corner blocks placed. Converted coordinates are rounded to whole blocks, because you cannot stand on a fraction of one.
Example calculation
You have a base at Overworld X 1200, Y 64, Z −450 and want a Nether tunnel to it:
Nether Z = −450 ÷ 8 = −56.25 → −56
Nether Y = 64 (unchanged)
Frame 4 × 5 = 10 obsidian, 6 portal blocks
Lava buckets = 10
So the matching Nether portal goes at 150, 64, −56. Enter those numbers above and you will see the same result. Coming back the other way, 150 × 8 = 1200 and −56 × 8 = −448 — two blocks off the original, which is the rounding, and close enough for the portals to link.
Frequently asked questions
What is the Nether coordinate ratio?＋
Every block you travel in the Nether covers eight blocks in the Overworld, so Overworld coordinates are divided by 8 to find the matching Nether spot and multiplied by 8 going the other way. The Y coordinate — your height — is not scaled at all.
How much obsidian does a Nether portal need?＋
A minimum portal is 10 obsidian: two along the bottom, two along the top and three up each side, with the four corners left out. Including the corners it is 14. The largest portal Minecraft accepts is 23 by 23, which needs 84 obsidian without corners.
Why does my portal link to the wrong place?＋
Minecraft looks for an existing portal within a search radius of the arrival point and reuses it rather than building a new one. If two Overworld portals are closer together than 1,024 blocks they can share one Nether portal — space them further apart, or build the destination portal yourself at the exact coordinates before travelling.
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Assumptions & limitations
Every figure here comes from a simplified model. Keep these limits in mind when reading your result:
- The 8:1 ratio is the vanilla default. Servers and modpacks can change it, and the End uses no coordinate scaling at all.
- Coordinates are rounded to whole blocks, so converting back and forth can shift you by a block or two — harmless for linking, but check the Y level is safe before you step through.
- Portal linking also depends on the game finding space to build. A portal placed inside a lava sea or a bedrock ceiling can still fail even at the right coordinates.
- Frames are limited to between 4 × 5 and 23 × 23, the range Minecraft will light.
- Lava-bucket counts assume the cast-in-place method with a water source; mining natural obsidian needs a diamond or netherite pickaxe instead.