|This feature is exclusive to Java Edition.|
Spawn chunks are chunks found in the world spawn point which are not unloaded from the memory, unlike normal chunks. They are not found in Legacy Console Edition. In Bedrock Edition, a similar mechanic is called ticking area.
Normally, old chunks beyond the render distance get unloaded from the memory and new chunks get loaded into the memory. Therefore, events such as redstone mechanisms and iron golem (Or otherwise any kind of) farms in old chunks stop processing. Because spawn chunks do not get unloaded, events occuring in them continue to process, even if no players are nearby. If the world spawn is set to a laggy area using commands, such as an area with many redstone clocks, lag is present wherever the player is in the world.
Events in spawn chunks do not process if no players are present in the Overworld for more than 15 seconds, although spawn chunks are not unloaded. However, the timer gets reset whenever an entity leaves or enters the Overworld. For example, continuously shooting arrows from dispensers in the Overworld through a nether portal causes events to continue to process, even if no players are in the Overworld.
The following events are processed regardless of player location, as long as the event is in a spawn chunk:
- Water and lava flow normally.
- Lava can start fires on nearby flammable objects.
- Fire spreads to any nearby flammable objects.
- Dropped items can fall, be moved by water or destroyed by lava, and despawn after 5 minutes if not picked up by a player or collected by a hopper.
- Passive mobs, such as baby animals and villagers, can grow into adults.
- Sand and gravel can fall if the block below is moved or destroyed.
- Villagers can breed if all conditions are met.
- Iron golems can spawn inside villages.
- Primed TNT can fall and explode.
- If the TNT reaches an unloaded chunk, it freezes and does not explode, therefore, no blocks in the unloaded chunk are affected until that chunk is loaded.
- Minecarts, hoppers, dispensers, and redstone mechanisms all operate normally.
Some events don't get processed until they are in the chunk update range, which varies on the render distance if in singleplayer, and is controlled by an operator in multiplayer, which includes the following:
- Plants (including crops, mushrooms, sugar cane, cacti, and saplings) do not grow.
- Ice neither forms nor melts.
- Hostile mobs instantly despawn if they spawn more than 128 blocks from any player.
- Passive mobs do not spawn naturally outside a 240 block X 240 block area around a player.
- The passive mob spawn cap is limited by the number of friendly mobs loaded into memory, which means that any passive mobs present in the spawn chunks count towards the mob cap and usually prevents friendly mobs from naturally spawning anywhere else in the world. The only exception is when passive mobs spawn as part of a newly generated chunk.
Spawn chunks normally consist of an area of 23×23 chunks in the world spawn point.[verify] The exact rule includes chunks whose center is less than or equal to 184 blocks away from the world spawn along both axes.[verify] In the rare case where the world spawn is located exactly on the border of a chunk, 24 chunks are loaded along that axis, and 20 of which activate entities. Entities are active only if all chunks in an area of 5×5 chunks around them are loaded, limiting their activities to an "effective area" of 19x19 chunks around the world spawn point. This leaves a 2 chunk wide border on the outskirts of the spawn chunks, in which entities are not processed, but redstone and other blocks continue to update. This is often referred as "lazy chunk loading".
There are several ways to determine the world spawn point:
- A compass always points to the spawn point.
- The following works only for players not connected to a bed:
- In Adventure mode, the northwest corner of the block players spawn on is the world spawn point.
- In Creative, Spectator, and Survival modes, players spawn on a random block in a 20×20 box centered on the spawn point. The spawn point can be inferred by repeatedly respawning and keeping track of the smallest rectangle encompassing all blocks players have spawned on so far. If the rectangle spawns between
a < bon both axes, the spawn point can be on any integer
b − 10 ≤ x ≤ a + 10with equal probability. Once the rectangle has grown to 20×20 blocks, the spawn point is in its exact center.
- Doing the commands
/gamerule spawnRadius 0then
- Entities other than players falling into the exit portal in the End land on the exact spawn point. Items thrown in mark the spot in the Overworld. Players spawn like they normally do, allowing this to be used to perform the above without dying.
- A new world spawn point can be set using
/setworldspawn. If no coordinates are provided, the northwest corner of the block the player is currently standing on becomes the spawn point. Note that this does not load the new spawn chunks; it merely prevents them from unloading. The chunks can be loaded by walking into range or restarting the server. They remain loaded until the spawn point is moved again.
- Mods or external programs such as NBTExplorer or MCEdit can also be used to find and set the world spawn point.
Comparison with ticking areas and
Instead of spawn chunks, Bedrock Edition has a game mechanic called ticking areas that serves a similar purpose. There is also a
/forceload command that serves similar purposes.[Java Edition only] However, there are a few differences. The following table contrasts spawn chunks and ticking areas.
|Property||Spawn chunks||Ticking areas||Force-loaded chunks|
|Number of areas supported||1||10||256|
|Position||Centered on world spawn point||Specified by player, by
||Specified by player, by |
|Size||17×17 maximum (289 chunks)||Specified by player; 1 to 100 chunks||Specified by player, 1 to 256 chunks|
|Dimensions where usable||Overworld||Any||Any|
|Grass and mycelium spread||No||Yes||No|
|Ice forms and melts||No||Yes||No|
|Hostile mobs spawn >128 blocks from player||No||Yes||Yes[verify]|
|Passive mobs spawn >240 blocks from player||No||Yes||Yes[verify]|
|Explosions break blocks in nearby chunks||No||Yes||Yes|