Seed (level generation)
Minecraft seeds are values made up of character(s) (including negative or positive integers) that are used as the basis for generating every Minecraft world.
- 1 Compatibility
- 2 World generation
- 3 Determining the seed
- 4 Technical
- 5 Video
- 6 History
- 7 Trivia
- 8 External links
- 9 References
Java Edition seeds between Alpha 1.2.0 and Beta 1.7.3 are mostly the same. Beta 1.8 changed world generation completely and Release 1.2 changed locations of land biomes with the addition of jungles. Release 1.7.2 rewrote the world generation entirely, making seeds from 1.2 through 1.6.4 outdated. 1.13 featured changes to cave generation, new aquatic biomes, and adjustment to mutated biome and structure locations. 1.14 included the new bamboo jungle biome and updated locations of villages and pillager outposts. Not mentioned are structure additions in several updates throughout, but the addition of a generated structure usually does not require a complete change of biome generation.
In Bedrock Edition, the Alpha 0.9.0 update was the only update to overhaul world generation. Oceans were changed in the Update Aquatic, and villages & other structures were changed in Village & Pillage.
Legacy Console Edition seeds were updated in a similar schedule to Java Edition equivalents.
Whenever the game has to generate a new world, it calls upon an algorithm. This algorithm outputs a pseudo-random value that is then used to determine the characteristics and features of the world. However, the algorithm always outputs the same value each time for a constant starting point (seed). This is why seeds exist — to generate entirely different worlds, consistently each time, from single values.
A world's seed is set when that world is created. By default, it is decided automatically, but it can also be set manually. Set and reuse a seed to replay that world, or use a known seed to play the same world as another player. Either a number or a word/phrase can be used, including negatives. If a word/phrase is used, it is converted into a 32-bit integer.
Whenever the world generation algorithm is updated (usually by adding new biomes to the game), the same seed no longer generates the same terrain. This is why in some different versions of the game, the same seed does not produce the same world. If the seed or generator changes in a saved world, new chunks are based on the new seed and no longer match those from the old seed. In Java Edition, major (terrain-breaking) changes were observed with Alpha v1.2.0, Beta 1.8, and 1.7.2. Deleted chunks can regenerate if the seed and generator remain the same, but changes if either the seed or generator changes. In fact, deleting chunks is sometimes done to let newly-introduced features appear in an old world; see Tutorials/Updating old oceans in 1.13 using MCEdit.
Because seeds are simply random values read into an algorithm and not actually names of different worlds, using a certain seed does not result in a world with any relevance to the value of that seed. For instance, using a biome name as the seed does not necessarily result in the creation of a world with primarily that biome, nor does it spawn the player within the said biome.
Determining the seed
In Bedrock Edition, the seed can be found on the world options screen. There is also a seed picker that offers the player several pre-set seeds to generate worlds with specific features near the spawn point. Additionally, the beta version has a visible seed on the top of the screen.
If the seed contains characters other than numbers or is greater than or equal to 20 characters in length, the Java
String.hashCode() function is used to generate a number seed. This restricts Minecraft to a subset of the possible worlds to 232 (or 4,294,967,296), due to the
int datatype used. Number seeds or a default world seed must be used to access the full set of possible worlds (264, or 18,446,744,073,709,551,616). There are 248 meaningful seeds because Java's
Random uses 48 bits of the seed; seeds are equivalent to one another modulo 248.
Bedrock Edition has a total of 232 (or 4,294,967,296) possible worlds no matter whether strings or numbers are used as the seed. This is because Bedrock Edition uses a 32-bit variant of the Mersenne Twister PRNG, which accepts only 32-bit seeds. The hashing algorithm is identical to
String.hashCode(): a hash h starts with 0, and for each character c, the value of h is changed to h * 31 + c, within the boundary of a 32-bit integer.
Overlap between editions
Positive seeds in the range 0–231 (0–2,147,483,648) generate the same arrangements of biomes in both Java and Bedrock editions, although with different structures and structure locations, caves, ore generation, and spawned entities, as well as minor terrain differences.
In Java Edition, the numeric entry for Minecraft seeds does not allow the number "0" (zero), as the game interprets "0" as a character, hashing it to its ASCII value of
48. However, by using a text seed for which the Java
String.hashCode() function returns a zero value, the "zero seed" can still be used. Word strings that produce a zero seed include
small skeleton, and
drumwood boulder head. However, any text that hashes to 0 works, such as
166lr735ka3q6. Numeric seeds that are congruent to 0 modulo 248 (such as
281474976710656) also generate the same terrain as seed 0, but do not display as 0 using
In Bedrock Edition, the game rejects all numbers from -9 to +9. However, changing the last character of the seed by one also changes the output hash code by one, so to arrive to a value of +2 from
small skeleton, the last letter is advanced two positions to become
small skeletop. The shortest version is still
ddnqavb, followed by any other letter from
Through certain seeds, it is possible to observe interesting effects.
Changing terrain without changing some structures
Only certain sections of the seed are used to generate specific features within the world. It is possible to generate multiple worlds with identical cave systems, Nether biomes and other arrangements of generated structures simply by converting the seed into binary and tweaking the desired bits. An example is the seed generator using only the first 48 bits to generate cave systems and badlands clay banding layers.
The biome distribution of one world is identical to the biome distribution of another world whose seed can be found by adding the constant
-7379792620528906219 to the current seed. The terrain generates differently in both worlds, however.
Certain seeds return 0 in the internal code, causing infinite arrays of caves and other structures to generate. In Java and Legacy Console editions, the seed
107038380838084 returns 0 on the first call and
164311266871034 returns 0 on the second call, causing mineshafts, caves and underwater ravines to loop on the X and Z axes respectively. Underwater caves and normal ravines will not repeat with this seed for 1.13 onwards, as a salt was unaccountably added for these. However, if 1 is subtracted from either seed, ravines and underwater caves will repeat, but the other three structures will not. It has been theorised that these seeds also may affect the layout of different block types in strongholds as well as clay patterns in badlands, however no conclusive evidence has been drawn from this yet.
Other features can also be broken, such as decorations. These instead generate diagonally.
|Java Edition pre-Classic|
|rd-160052||Added a simple level generator.|
|Java Edition Classic|
|0.0.12a||Added a new level generator.|
|August 25, 2009||Showed another new level generator, which generates cliffs more commonly.|
|Java Edition Indev|
|0.31||20091223-2||Isometric level rendering screenshot added.|
|20100106||The player can now select island, floating, flat, or original as the level type when generating a world.|
|Players can also select square, long, or deep as the level shape.|
|Players can also select small, normal, or huge as the level size.|
|20100107||Deep floating maps now have layers of islands.|
|Players can now select a level theme; normal or hell.|
|20100111-1||Islands now generate with more sand.|
|20100113||Oceans now generate with infinite water.|
|20100122||Water now spawns naturally above sea level and on floating islands.|
|Caves are now less flooded.|
|Java Edition Alpha|
|v1.2.0||?||Terrain-breaking change to world gen: using any given seed on older versions now generates a different world.|
|Java Edition Beta|
|1.3||It is now possible to manually determine the seed upon world creation.|
|1.8||Pre-release||Terrain-breaking change to world gen. The debug screen now displays the seed number.|
|1.2.1||?||Multiplayer servers no longer send the seed to clients.|
|1.3.1||12w18a||Due to singleplayer becoming multiplayer, the world's seed is no longer displayed on the debug screen.|
|1.7.2||13w36a||Terrain-breaking change to world gen. Seed types were changed.|
|1.13||18w06a||World generator rewritten in a non-breaking way. Customized removed.|
|Pocket Edition Alpha|
|v0.9.0||?||Changed terrain generation, making old seeds outdated|
- If a user modifies the Java Edition source code for any version between 1.7.2 and 1.12.2, and change a value[more information needed] from 2 to 0 for the 6th genlayer, a user can replicate biome generation from Legacy Console Edition on Java edition with the exception of mushroom biomes.
The following map seeds have, at one point or another, been used for generating official Minecraft maps and resources.
- In Java Edition, the demo world seed can be played in the full version by entering
North Carolinain the seed input.
- In Java Edition, the seed for the title screen panorama between Beta 1.8 Pre-release and 18w22c is either
8091867987493326313, generated between Beta 1.6.6 and Beta 1.7.
- In Java Edition, the seed for the original pack.png file is
3257840388504953787, generated in Alpha v1.2.2. It can also be generated between Alpha v1.2.0 and Beta 1.7.3 with minor population differences.
- In Java Edition, the seed for the Skull on Fire painting is either
-1044887956651363087, generated in Alpha v1.1.2_01 or prior.
- Random Seed Reader: Local Java tool
- AMIDST Project: Seed/map explorer tool
- Chunkbase Minecraft Apps: Another seed/map explorer tool
- MineAtlas Seed/map explorer/finder tool
- Minecraft Seeds: Community-driven Minecraft Seeds
- Minecraft Seed HQ: Seeds by Minecraft Version
- LookingForSeed Find Minecraft seeds from various categories
- SeedCracker guess a seed from a multiplayer server
- "The world with that same name on the screenshot uses seed "pollinating sandboxes" as well, a legit way to create a world with seed 0. Other strings that create seed 0 are "creashaks organzine" and "drumwood boulderhead" but I used one that's easy to remember." – @SeargeDP