SeedariSeedari

Accuracy report

How accurate is the Seedari seed map?

On Java 26.3, 1,320 of 1,320 structure positions we checked were in the same chunk as on the official Minecraft server: 22 structure types, including strongholds, nether fortresses, bastions and end cities, on 20 held-out seeds (checked November 10, 2026).

We ran the official Minecraft server, asked it where structures, biomes and the spawn point are, and asked our map the same questions. The test used 20 seeds that none of the map's rules were ever tuned on.

Tested November 10, 2026 · Java Edition 26.3 and 1.21.4

Structures in the same chunk
100%2,580 / 2,58022 structure types, looked up from 3 places in every seed
Biome points that match
99.8%1,198 / 1,20030 points in every seed, at Y 64
Spawn points on the same block
100%40 / 40Compared with the spawn the server saves in the world file

How we tested

  1. 1

    The official server, unchanged

    Mojang's own server for Java 26.3 and 1.21.4, checked against Mojang's published checksum. One new world per seed, no mods or plugins. It runs on automated test machines and is deleted after each run.

    Source: minecraft.net

  2. 2

    Seeds the map was never tuned on

    The map's structure rules were worked out on a different set of seeds. The 20 seeds in this test were fixed in advance by a public rule, a hash of a fixed phrase, and nothing in the map was changed after the run.

  3. 3

    Every structure type, one by one

    From 3 places in every seed we asked the game for each structure type with /locate and ran the map's engine through the same search. A match means the same chunk. Then we took each answer the map's Find nearest gives and asked the game whether that structure is really there.

    Source: Minecraft Wiki

  4. 4

    Biomes and the spawn point

    30 points in every seed, up to 4,000 blocks from the center, checked with the game's own biome test at Y 64, the height the map draws. The spawn point is read from the world file the server writes.

    Source: Minecraft Wiki

Results by version

Java 26.3
Structures, same chunk100%1,320 / 1,320
Find nearest answers found in game100%1,320 / 1,320
Biome points99.8%599 / 600
Spawn, same block100%20 / 20
Java 1.21.4
Structures, same chunk100%1,260 / 1,260
Find nearest answers found in game100%1,260 / 1,260
Biome points99.8%599 / 600
Spawn, same block100%20 / 20

/locate doesn't always return the nearest structure. When the map's Find nearest named a different one, we asked the game about that spot directly, and the structure was there every time.

Results by structure

Each structure type was looked up 20 × 3 times per version: every seed, from every starting place.

  • Stronghold26.360/601.21.460/60
  • Village26.360/601.21.460/60
  • Trial Chambers26.360/601.21.460/60
  • Ancient City26.360/601.21.460/60
  • Woodland Mansion26.360/601.21.460/60
  • Ocean Monument26.360/601.21.460/60
  • Pillager Outpost26.360/601.21.460/60
  • Desert Pyramid26.360/601.21.460/60
  • Jungle Temple26.360/601.21.460/60
  • Witch Hut26.360/601.21.460/60
  • Igloo26.360/601.21.460/60
  • Abandoned Camp26.360/601.21.4—
  • Trail Ruins26.360/601.21.460/60
  • Ruined Portal26.360/601.21.460/60
  • Shipwreck26.360/601.21.460/60
  • Ocean Ruins26.360/601.21.460/60
  • Buried Treasure26.360/601.21.460/60
  • Mineshaft26.360/601.21.460/60
  • Nether Fortress26.360/601.21.460/60
  • Bastion Remnant26.360/601.21.460/60
  • Ruined Portal (Nether)26.360/601.21.460/60
  • End City26.360/601.21.460/60

Large Biomes worlds

The same test on the first 10 held-out seeds, in worlds created with the Large Biomes world type. Only Overworld structures were compared: the Nether and the End of a Large Biomes world are the same as in a default world.

Java 26.3
Structures, same chunk99.2%536 / 540
Find nearest answers found in game99.2%534 / 538
Biome points100%300 / 300
Spawn, same block90%9 / 10
Java 1.21.4
Structures, same chunk99.2%506 / 510
Find nearest answers found in game99.2%504 / 508
Biome points100%300 / 300
Spawn, same block90%9 / 10

Every difference was in a place where the game checks the ground. Three woodland mansions and one desert pyramid stand over a hollow below sea level that the game leaves dry, while the map assumes water there. Two ruined portals the map named sit over the deep dark, where the game checks the biome at the portal's buried height. One spawn point is off because the map's spawn search uses rough heights and passed over dry ground at Y 62. The map has the same gaps in default worlds; they are rare, and the default-world test above didn't run into them.

Bedrock Edition (beta)

Bedrock builds Overworld biomes from the same climate noise as Java, so the beta map draws them with the matching Java engine, one biome per 4×4 cell as Bedrock does. We checked it against the official Bedrock Dedicated Server on the same 20 held-out seeds and biome points as the Java test.

VersionBiome pointsSpawn, same chunkSpawn, same block
Bedrock 26.60 – 26.63Server build 1.26.63.195.1%571 / 600100%20 / 2050%10 / 20
Bedrock 1.21.120 – 1.21.132Server build 1.21.132.395.1%571 / 600100%20 / 2050%10 / 20

On both builds the same 29 biome points differ, all on the edge between two biomes: the map draws that edge a cell or so off. We haven't found the cause yet and are measuring it on the server. Structures are not on the Bedrock map yet: Bedrock places them differently from Java, and they will be added once they match the official server.

What didn't match

  • No structure: the map and the game named the same chunk in all 2,580 lookups.

  • One biome point, seed 8205759525615393039 at X 2356, Z 782 (26.3 and 1.21.4): the map shows Windswept Savanna, the game has Plains. The point is on the edge of a small Windswept Savanna patch, and the map draws that edge one biome cell (4 blocks) off here.

    Open this spot on the map

What this test doesn't cover

  • Two versions were run, Java 26.3 and 1.21.4. The other versions use the same engine but were not checked against the server.
  • It checks the chunk a structure starts in, not its shape, rooms or loot.
  • Desert wells, amethyst geodes and end gateways were not compared, because /locate can't find them.
  • Biomes were checked at Y 64 only, so cave biomes deeper down are not part of this test.
  • 60 lookups per structure type and version. A difference rarer than that could slip through.
  • Large Biomes worlds were tested on 10 seeds, and Bedrock Edition on biomes and the spawn point only (see above).

Check it yourself

These are the 20 seeds from the test. Open one on the map, then compare it with /locate in a world of your own.