Nether Portal Calculator
Convert coordinates between the Overworld and the Nether (the 1:8 ratio), count the obsidian for any portal size, and check which portal a new one will link to using the real Java and Bedrock search rules. The diagram shows both dimensions side by side and updates as you type.
Edition changes the portal search area: Java 1.16.2+ searches 128 blocks each way in the Overworld and 16 in the Nether; Bedrock searches 128 in both.
Coordinate converter
Type in either row and the other updates. X and Z are divided by 8 (rounded down) going in and multiplied by 8 coming out. Y never changes.
Portal linking checker
List the portals you already have (either dimension, one row each), then enter the portal you plan to build. The checker applies the real search rules for Java 1.16.2+: a square 257×257 area in the Overworld and 33×33 in the Nether around the scaled target, full height, closest portal by straight-line distance including Y.
Existing portals
Planned portal
Spawn hub (Nether) (Nether 0, 64, 0) is inside the search area (12 blocks from the target), so this portal connects to it. From Spawn hub (Nether) the game targets 0, 64, 0 and the closest portal there is Spawn hub (Overworld 0, 64, 0), not this one.
12, 64, 0
16 blocks each way (33×33)
Spawn hub
| Nether portal | Position | Distance from target | In search area |
|---|---|---|---|
| Spawn hub (Nether)linked | 0, 64, 0 | 12.0 | yes |
Verified: it sits at distance 0 from the target, so this portal always picks it, the way back lands here, and no existing link is redirected.
Spacing guide for Java: two Overworld portals at least 264 blocks apart, or two Nether portals at least 33 blocks apart, always get separate auto-generated partners. Closer is fine when you build both sides by hand. Coming from the Nether the exact target moves by up to 7 Overworld blocks depending on where in the portal block you stand.
Both maps show the same area at 1:8 (the Nether panel covers 128 blocks across, the Overworld panel 1024). Diamond = planned portal, dots = existing portals, crosshair = scaled target, solid square = the search area for the trip through the planned portal, dashed square = the search area for the way back, ring = the portal each trip picks.
Obsidian calculator
Outer frame size in blocks, including the frame itself. Any rectangle from 4×5 up to 23×23 works on Java and Bedrock. The four corners are optional.
Portal distance
Straight-line distance between two points, the same measure the game uses to pick the closest portal.
How Overworld and Nether coordinates work
Travelling one block in the Nether moves you eight blocks in the Overworld, so the Nether is an 8× fast-travel layer. To find where an Overworld location lands in the Nether, divide its X and Z by 8 and round down (Java floors toward negative infinity, so -1 becomes -1). The Y coordinate is identical in both dimensions and is never divided. To go the other way, multiply the Nether X and Z by 8. Results are clamped to the world border, which only matters beyond X or Z ±3,749,998 in the Nether.
Worked example 1: a clean two-way pair
Your base is at Overworld X 1480, Y 64, Z -520. Divide X and Z by 8: 1480 / 8 = 185 and -520 / 8 = -65, so the Nether target is 185, 64, -65. Travel there in the Nether, build a 4×5 frame (10 obsidian without corners) and light it. Each portal now sits exactly on the other one’s scaled target, at distance 0, so both trips pick the right portal no matter what else is nearby, unless another portal sits on the very same spot.
Worked example 2: a portal that links to the wrong place
You have a spawn hub pair: Overworld 0, 64, 0 and Nether 0, 64, 0. You build a new Overworld portal at 100, 64, 0. Its target is 12, 64, 0, and on Java the Nether search covers 16 blocks each way, so the hub’s Nether portal 12 blocks away is inside it: your new portal links to the hub. The way back is worse: from the hub’s Nether portal the game targets Overworld 0, 64, 0, where the hub portal sits at distance 0 and yours is 100 blocks away, so you come out at spawn. A one-way trip.
The fix is to build a Nether portal yourself at 12, 64, 0. It is at distance 0 from your new portal’s target, so it always wins, and its own return target 96, 64, 0 is 4 blocks from your portal but 96 from the hub, so it comes back to you. The hub keeps its own links. On Bedrock the same portal built at X 400 (target 50) would still link to the hub, because the Nether search reaches 128 blocks; only a portal beyond X 1032 (target 129) gets its own pair automatically. This layout is loaded in the checker above, switch the edition to compare.
How portal linking works (the search area)
When you step through a portal, the game scales your coordinates (÷8 or ×8) and looks for existing portals in a square area around that spot, across the full world height. It then picks the closest one by straight-line distance, including Y. On Java 1.16.2+ the area is 16 blocks each way arriving in the Nether (a 33×33 column) and 128 each way arriving in the Overworld (257×257), which matches the 1:8 scale. On Bedrock it is 128 each way in both dimensions, so a Nether-side search covers the equivalent of 2048 Overworld blocks, which is why Bedrock portals take over each other so much more often. If nothing is found, the game generates a 4×5 portal within 16 blocks of the target.
| Rule | Java 1.16.2+ | Bedrock |
|---|---|---|
| Coordinate ratio | 1 Nether block = 8 Overworld blocks, Y unchanged | Same |
| Search area arriving in the Nether | 16 blocks each way (33×33 columns) | 128 blocks each way (257×257 columns) |
| Search area arriving in the Overworld | 128 blocks each way (257×257 columns) | 128 blocks each way (257×257 columns) |
| Overworld spacing for separate auto-generated portals | At least 264 blocks | At least 2056 blocks |
| Nether spacing for separate auto-generated portals | At least 33 blocks | At least 33 blocks |
| Frame sizes | 4×5 to 23×23, corners optional | Same |
| Who can create a new portal | Almost any entity except withers and the ender dragon | Players only |
| Forced portal platform | 2×3 obsidian | 2×3 obsidian plus netherrack on each side |
Rules from the Minecraft Wiki pages Nether Portal and Tutorial: Nether portals.
How to build a linked Nether portal pair
- Note the first portal’s coordinates. Stand inside the lit portal and read X, Y and Z: press F3 on Java, or turn on Show Coordinates in the world settings on Bedrock.
- Scale the coordinates. Divide X and Z by 8 and round down for the Nether side, or multiply by 8 for the Overworld side. Keep Y the same. The converter above does this.
- Check the link. Enter your existing portals and the planned position in the linking checker. If it would link to another portal, move it or plan to build both sides by hand.
- Gather the obsidian. 10 blocks for a 4×5 frame without corners, 14 with corners, plus flint and steel. Use the obsidian calculator for bigger frames.
- Travel to the scaled coordinates. In the other dimension, dig or bridge to the exact X and Z and stay at the same Y. A portal placed exactly on the target is at distance 0, so it always wins.
- Build and light the frame. Place the obsidian frame at that spot and light it with flint and steel.
- Test both directions. Walk through each portal and confirm you arrive at the other one. If not, re-check for a closer portal with the linking checker.
Placing the partner portal yourself, instead of letting the game generate one, is the reliable way to get a clean two-way link. The game can put a generated portal up to 16 blocks away and at any height, and that offset is what lets other portals get in between.
FAQ
How do you convert Overworld coordinates to the Nether?
Divide X and Z by 8 and round down; Y stays the same. Overworld X 1480, Z -520 becomes Nether X 185, Z -65. Going the other way, multiply the Nether X and Z by 8. Negative numbers also round down, so Overworld X -1 becomes Nether X -1, not 0.
Why does my Nether portal link to the wrong portal?
When you enter a portal the game scales your position (divide by 8 or multiply by 8), then looks for any existing portal in a square area around that target: on Java 16 blocks each way in the Nether and 128 each way in the Overworld, on Bedrock 128 each way in both. It picks the closest one by straight-line distance, counting height. If another portal sits inside that area and is closer than the one you meant, it wins. The fix is to build the partner portal yourself at the exact scaled coordinates: a portal at distance 0 always wins. The linking checker above tells you which portal a planned one would pick.
How far apart do Nether portals need to be?
To be sure two Overworld portals get separate Nether portals without any manual building, keep them at least 264 blocks apart on Java (their two 33×33 Nether search areas can then never overlap) and at least 2056 blocks apart on Bedrock (search radius 128 in the Nether). Two Nether portals need at least 33 blocks between them on either edition. Portals can be much closer than that, even 8 blocks, as long as you build both sides by hand at the scaled coordinates.
Does Y (height) matter for Nether portals?
Y is never divided or multiplied, so a portal at Y 64 targets Y 64 in the other dimension. Height does count when the game picks the closest portal, because the distance is measured on all three axes: a portal 40 blocks below the target loses to one 20 blocks away horizontally, and two portals can share X and Z at different heights and still link separately. Build the partner at the same Y whenever you can.
How does the portal search work exactly?
Java 1.16.2 and later: arriving in the Nether the game checks a 33×33 block square (16 each way) around the scaled target, arriving in the Overworld a 257×257 square (128 each way), both across the full world height. Bedrock checks 128 each way in both dimensions. Before 1.16.2 Java also used 128 in the Nether, which is why older guides say portals interfere within 1024 blocks.
What happens if no portal is found?
The game builds a new 4×5 portal, corners included, at the closest valid spot within 16 blocks horizontally of the target, at any height with room. If there is no room it forces a portal at the target on a small obsidian platform (Bedrock adds netherrack around it), which is how portals end up floating or buried.
How many obsidian blocks do I need for a Nether portal?
The smallest portal is 4 wide and 5 tall: 10 obsidian without the corners or 14 with them. For any size the frame takes 2 × (width + height) − 4 blocks with corners, and 4 fewer without. The largest portal, 23×23, takes 84 or 88. The obsidian calculator above covers every size in between.
What is the biggest and smallest Nether portal size?
On both Java and Bedrock the frame can be any rectangle from 4×5 up to 23×23 blocks (outer size), so the opening ranges from 2×3 to 21×21. Portals cannot be built lying flat.
Is the Nether ratio the same on Bedrock?
Yes, 1 Nether block equals 8 Overworld blocks on both editions and Y is unchanged. What differs is the search area: Bedrock looks 128 blocks each way in the Nether where Java only looks 16, so Bedrock portals take over each other far more often. Use the Bedrock toggle above.
Why do I come out at a different Overworld portal from the same Nether portal?
A portal is 2 blocks wide and each block has its own target when multiplied by 8, so the two columns can point at Overworld spots 8 blocks apart. If two Overworld portals are about equally close, the column you walk through decides where you land. Build the pair at the exact scaled coordinates, or move the two Overworld portals further apart.