Monster Spawner

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Monster Spawner
Monster Spawner.gif


Solid Block






Partial (doesn't block light)


No (Small amount of light for Pocket Edition)

Blast resistance





A wooden pickaxe or better is required to mine this block




Yes (64)



First appearances

See History


Mined: 15–43



Block Entity ID


Data value

dec: 52 hex: 34 bin: 110100



Monster spawners are blocks that can spawn mobs.

Obtaining[edit | edit source]

Spawners cannot be obtained in survival mode, even if Silk Touch is used. However, if mined without a pickaxe, the mining will be slower and the spawner will not drop any experience.

Monster Spawner
Hardness 5
Breaking time[note 1]
Hand 25
Wooden 3.75
Stone 1.9
Iron 1.25
Diamond 0.95
Golden 0.65
  1. Times are for unenchanted tools in seconds.

It is also not in the creative inventory (except in Pocket Edition), and pick block will not work on it, and as such must be obtained with commands. However, unlike many other blocks, it is still available as an item when obtained through such commands.

Natural generation[edit | edit source]

Spawners can generate naturally in these places, spawning mobs chosen randomly when generated:

It may be a zombie spawner (50% chance), skeleton spawner (25%), or spider spawner (25%).
Abandoned mine shafts
Cave spider spawner heavily surrounded by cobwebs.
Silverfish spawner. Located in the end portal room. One per stronghold.
Nether fortresses
Blaze spawner. Located on nether fortress balconies with stairs leading up to them. Normally two per fortress.

Usage[edit | edit source]

The monster spawner spawns mobs in an 8*8*3 area around it when the player is within 16 blocks of the spawner, provided suitable spawning locations for the block's mob type can be found in the area. The block will attempt to spawn 4 mobs around it, then wait from 10 to 39.95 seconds before spawning again.

When obtained as an item and placed, it will spawn pigs by default in the computer edition, or will appear empty in Pocket Edition.

The spawned mob can be changed by using a spawn egg on the spawner.

In Peaceful difficulty, monster spawner blocks will still appear and work, but any spawned hostile mobs will disappear the instant they spawn. Zombie pigmen, magma cubes, and ghasts will not spawn at all.

Monster spawners are transparent in their rendering only - unlike most other transparent blocks, they can have torches and redstone placed on them, conduct a redstone current, will suffocate mobs, and more.

Spawners cannot be moved by pistons.

Mechanics[edit | edit source]

A monster spawner is only active when a player is within a radius of 16 blocks from the spawner. While the block is active, it will spawn mobs within an 8×3×8 block volume (8 wide, 8 long, and 3 high) centered on the center of the block, effectively meaning mobs can spawn in a 9×9 area, or 3.5 blocks from the spawner. Mobs can spawn anywhere in this range that is suitable, with mobs more likely to spawn closer to the spawner than farther away.

While mobs are spawned at fractional x and z-coordinates (i.e. not aligned to blocks), they are spawned at an integer y-coordinate. Horizontally, a mob can spawn with its center point anywhere within the 8×8 range, but vertically, mobs will spawn with their legs at either the same layer as the spawner block, one block above it, or one block below it.

For some types of mobs to spawn in the outer planes of the spawning volume, some planes outside the volume may also need to be free of opaque blocks to conform with the mobs' height, width, or other rules governing their individual spawn volumes. For mobs that are two or more blocks tall such as zombies, skeletons, or blazes to spawn in the top y-layer, the layer above that must contain only air.

Summary of maximum spawn volumes for common monster spawners
Mob type Required Volume Failure rate from 8×8×4 volume[note 1] Vertical

8.9 × 8.9 × 2.9 2.531252%

Cave Spider
8.7 × 8.7 × 2.5 1.531252%

8.3 × 8.3 × 2.7 0.28125%



8.6 × 8.6 × 3.8 1.125%

9.4 × 9.4 × 2.9 6.125%

  1. 8×8×3 is the actual volume across which spawners spawn entities, but this volume only contains the entity's center. The failure rate assumes 8×8×4 because it is a popular misconception that 8×8×4 is the maximum efficiency volume of empty space for mob spawners - it actually depends on the size of the entities themselves. Note that 10×10×4 is guaranteed to accommodate all of the above mobs. Also note that this failure rate only accounts for failures due to attempting to spawn a mob at the edges of the spawn range, not other causes of failure such as mobs attempting to spawn intersecting the spawner block itself.

For all of the volumes listed in the table, the horizontal plane is centered on the center of the spawner block. While the spawning volume for pigs is 8.9×8.9×2.9, the requirement of grass blocks that are necessary for pigs to spawn will reduce the actual volume in which they successfully spawn, however other mobs can spawn in mid-air, ignoring general rules about spawning on solid ground.

The spawner does not have to be within 4 blocks of the correct biome for it to spawn mobs. As such, spawners can place mobs where they normally wouldn't generate. For example, a mooshroom spawner will operate in a plains biome as long as there are any mycelium blocks within the spawn area.

The block will attempt to spawn 4 mobs at randomly chosen points within the spawning area, then wait anywhere from 200 to 799 ticks (10 to 39.95 seconds) before spawning again. As it waits, the mob inside the block will spin faster and faster. Except for spawning on a solid block, all of the usual requirements for spawning must be met (not in a solid block, correct light level, etc.), so the spawner will often produce fewer than 4 mobs. When it does spawn, it will "poof", and more lightless flames will temporarily appear around the Spawn block. If the block fails to spawn any mobs because it did not pick any suitable locations, it will repeat this process every tick until it succeeds. Only when it manages to spawn at least one mob will it start waiting for the next cycle. If, at the time of spawning, 6 or more mobs of the spawner's type are present within a 9×9×9 area, centered on the spawner block, the spawner "poofs" without creating any mobs and then waits for the next cycle.

When mining near a monster spawner that has no valid places to spawn, sometimes a monster will spawn immediately after a block is mined.

Custom spawners[edit | edit source]

Monster spawners are capable of much more than they are used for in survival Minecraft. Using commands, they can be customized in many ways:

  • They can be made to spawn any kind of entity.
  • A single spawner can spawn multiple different entities, chosen at random from a list.
  • Properties can be set on the spawned entities.
  • Various range and timing properties of the spawner can be changed.

Detailed technical information about custom spawners can be found below.

Data values[edit | edit source]

See also: Block entity format

A monster spawner has a block entity associated with it that holds additional data about the block. The block's block entity ID is MobSpawner.

  • Block entity data
    • Tags common to all block entities see Template:Nbt inherit/blockentity/template

    •  SpawnPotentials: Optional. List of possible entities to spawn. If this tag does not exist, but SpawnData exists, Minecraft will generate it the next time the spawner tries to spawn an entity. The generated list will contain a single entry derived from the EntityId and SpawnData tags.

      • : A potential future spawn. After the spawner makes an attempt at spawning, it will choose one of these entries at random and use it to prepare for the next spawn.

        •  Type: Overwrites EntityId when preparing the next spawn.

        •  Weight: The chance that this spawn will be picked as compared to other spawn weights. Must be non-negative and at least 1.

        •  Properties: Overwrites the contents of SpawnData when preparing the next spawn. Not optional; an empty one will be created if it does not exist.

    •  EntityIddeprecated in 1.9[upcoming]: The Entity ID of the next entity(s) to spawn. Both mob entity IDs and other entity IDs will work. Warning: If SpawnPotentials exists, this tag will get overwritten after the next spawning attempt: see above for more details. From 1.9[upcoming], use the "id" tag inside SpawnData (see below).

    •  SpawnData: Contains tags to copy to the next spawned entity(s) after spawning. Any of the entity or mob tags may be used. Note that if a spawner specifies any of these tags, almost all variable data such as mob equipment, villager profession, sheep wool color, etc., will not be automatically generated, and must also be manually specified (note that this does not apply to position data, which will be randomized as normal unless Pos is specified. Similarly, unless Size and Health are specified for a Slime or Magma Cube, these will still be randomized). This, together with EntityId, also determines the appearance of the miniature entity spinning in the spawner cage. Note: this tag is optional: if it does not exist, the next spawned entity will use the default vanilla spawning properties for this mob, including potentially randomized armor (this is true even if SpawnPotentials does exist). Warning: If SpawnPotentials exists, this tag will get overwritten after the next spawning attempt: see above for more details.

    •  SpawnCount: How many mobs to attempt to spawn each time.

    •  SpawnRange: The radius around which the spawner attempts to place mobs randomly. The spawn area is square, includes the block the spawner is in, and is centered around the spawner's x,z coordinates - not the spawner itself. It is 2 blocks high, centered around the spawner's y coordinate (its bottom), allowing mobs to spawn as high as its top surface and as low as 1 block below its bottom surface. Vertical spawn coordinates are integers, while horizontal coordinates are floating point and weighted towards values near the spawner itself. Default value is 4.

    •  Delay: Ticks until next spawn. If 0, it will spawn immediately when a player enters its range. If set to -1 (this state never occurs in a natural spawner; it seems to be a feature accessed only via NBT editing), the spawner will reset its Delay, and (if SpawnPotentials exist) EntityID and SpawnData as though it had just completed a successful spawn cycle, immediately when a player enters its range. Note that setting Delay to -1 can be useful if you want the game to properly randomize the spawner's Delay, EntityID, and SpawnData, rather than starting with pre-defined values.

    •  MinSpawnDelay: The minimum random delay for the next spawn delay. May be equal to MaxSpawnDelay.

    •  MaxSpawnDelay: The maximum random delay for the next spawn delay. Warning: Setting this value to 0 crashes Minecraft. Set to at least 1.

    •  MaxNearbyEntities: Overrides the maximum number of nearby (within a box of spawnrange*2+1 x spawnrange*2+1 x 8 centered around the spawner block) entities whose IDs match this spawner's entity ID. Note that this is relative to a mob's hitbox, not their physical position. Also note that all entities within all chunk sections (16x16x16 cubes) overlapped by this box are tested for their ID and hitbox overlap, rather than just entities which are within the box, meaning a large amount of entities outside the box (or within it, of course) can cause substantial lag.

    •  RequiredPlayerRange: Overrides the block radius of the sphere of activation by players for this spawner. Note that for every gametick, a spawner will check all players in the current world to test whether a player is within this sphere. Note: Requires the MaxNearbyEntities property to also be set.

Video[edit | edit source]

History[edit | edit source]

Seecret Friday 2 Monster Spawner-Pre Beta 1.9.png Added mob spawners. They could be picked up and when placed, spawned pigs.
June 27, 2010 Mob spawners given a unique ID, reducing crashes.
? Changed name from mob spawner to monster spawner.
1.2 Monster spawners again now show a rotating model inside of what they spawn in single player after being missing for several versions.
Official release
1.0.0 Beta 1.9-pre1 Monster Spawner.png Changed monster spawner texture to a darker color.
Beta 1.9-pre3 Spawners will now drop when mined using a tool enchanted with the new Silk Touch enchantment.
Beta 1.9-pre5 Squid spawners now only work in a narrow elevation range, from 46 to 62.
Monster Spawners no longer drop when broken using a tool enchanted with Silk Touch.
Beta 1.9-pre6 Monster spawners are now easier to destroy.
1.2.1 12w06a Monster spawners now show the mob they are spawning in multiplayer; previously it always showed a pig.
1.3.1 12w22a Monster spawners will now drop experience when destroyed.
12w26a Monster spawners now support extra data pertaining to what they spawn.
1.8 14w26c The horizontal spawning range is now calculated from the center of the block rather than the northwest corner.
The exclusion zone has been reduced: for a default spawner, the 6 mobs must be in a 9×9×9 region rather than 17×9×17 to prevent spawning.
14w28b The type of mob spawner can be changed by using a spawn egg on it.
1.9 16w02a A spawner containing a large mob will now scale down the mob to fit inside the spawner block.
Pocket Edition Alpha
0.9.0 build 1 Added monster spawners.
build 2 Added monster spawners to the creative inventory. The type of mob spawner can be changed using a spawn egg.
build 9 Monster spawners now emit light.
Console Edition
TU1 CU1 1.0 Added monster spawners.
TU31 CU19 1.22 The type of mob spawned can now be changed by using a spawn egg.

Issues[edit | edit source]

Issues relating to “Monster Spawner” are maintained on the issue tracker. Report issues there.

Trivia[edit | edit source]

  • If a spawner is made to spawn a giant, ghast, enderman, or iron golem; the mob inside will be larger than the spawner and will appear to physically extend beyond the confines of the spawner block's sides. If a spawner is made to spawn endermen, the head will poke through the block. This does not happen in Pocket Edition or in 1.9[upcoming], as mob figures inside spawners are scaled to the size of the block. [Verify]
  • The miniature mob inside the monster spawner is an actual mob of that type. Thus, if a spawner is configured to spawn ender dragons or withers, their boss health bar is visible while looking at the spawner.
  • In Pocket Edition or PC version, spawners containing zombies or skeletons have a chance for the mob spinning inside to have armor.
  • If there is a spawner in a MushroomIsland or MushroomIslandShore biome, the spawner will still run.

Gallery[edit | edit source]

See also[edit | edit source]