Minecraft Mob Spawner

Monster spawner or mob spawner blocks are dark blue cubical cages that contain a fire texture and a spinning miniature mob model. The small mob inside the spawner represents the type of mob that the block will generate. The tiny mob spins faster and faster until the spawner releases a mob. Mob spawners can be found in Nether fortresses, abandoned mine shafts, dungeons and strongholds. There are only a few types of mob spawners in naturally generated maps. Without using a custom map or inventory editor, spawners can spawn blazes, silverfish, spiders, zombies, skeletons and cave spiders.

Mob spawners may be a nuisance when you are trying to pillage a newly found dungeon, but they are invaluable for farming items that can only be dropped by mobs. You can place traps around the spawner such as a long fall, cactus, drowning or a combination to kill mobs as they spawn to farm resources.


Type: Solid Block
Requirements: None
Physics: No
Transparency: Yes
Luminance: No
Blast Resistance: 25
Tool: Pickaxe
Renewable: No
Stackable: Yes (64)
Data Value- Dec: 52, Hex: 34

Minecraft Mob Spawner


Mob spawners appear in several types of natural structures. Only certain mob spawners can appear in each type of structure.

  • Dungeons: Zombie, skeleton and spider spawners. The mob spawner type is chosen at random (zombie spawners are the most common) and only one can appear per dungeon. 50% chance of zombies, 25% chance of spiders and 25% chance of skeletons.
  • Abandoned Mine Shafts: Cave spider mob spawners appear behind layers of cobweb throughout mineshafts.
  • Strongholds: Every stronghold has a silverfish mob spawner near its End Portal.
  • Nether Fortresses: Blaze mob spawners appear in the nether strongholds. They are usually found on raised platforms exposed to the open air.

Skeleton Monster Spawner

Players cannot gather or place monster spawners in survival mode without the assistance of mods. Server administrators can add various types of mob spawners by editing the server, or by downloading plugins that allow mob spawners. Even in creative mode, you cannot select and place mob spawners from your inventory.

Detailed Spawning Algorithm

every spawn cycle (every randInt(200,799) ticks when a player is within
17 blocks of the spawner),
loop 4 times {
if there are 6 or more of the mob type in the 17x9x17 area around the spawner,
skip this spawn cycle
calculate spawnerX = X coordinate of center of spawner – 0.5
calculate spawnerY = Y coordinate of center of spawner – 0.5
calculate spawnerZ = Z coordinate of center of spawner – 0.5
calculate x coordinate of mob = spawnerX + (randDouble() – randDouble()) * 4,
randDouble being a random number between 0 and 1
calculate y coordinate of mob = spawnerY + a random integer between -1 and 1
calculate z coordinate of mob = spawnerZ + (randDouble() – randDouble()) * 4,
randDouble being a random number between 0 and 1
if all of the conditions specific to the mob type are met, spawn the mob {
chicken, cow, mooshroom, pig, sheep, wolf:
block below spawning block is grass
spawning block has a light level of 9 or higher

pass a 2/3 random test
block below spawning block is grass or leaves
on layer 63 or higher

creeper, enderman, skeleton, spider, cave spider, zombie:
light level 8 or less

light level 8 or less, no players within 5 blocks

difficulty is not set to peaceful or slime size is small
spawn block y coordinate is less than 40
the chunk containing the spawn block is a slime chunk (1 in 10 chance)
pass a 1 in 10 random test

pass a 1 in 20 random test

must not collide with any other entities
must be in layer 46-62

all except squid and slimes:
must not collide with any blocks or other entities
must not collide with water or lava
if all 4 mobs failed to spawn, repeat on the next tick

Blaze Monster Spawner in a Fortress

Spawning Behavior

Spawners can only generate mobs as long as the area around it meets the ordinary criteria for spawning that mob type. Most hostile mobs from the Overworld, like skeletons and zombies, can only spawn in light level 7 or lower. Animal spawners only generate mobs if there is grassy dirt around it. If there are more than 5 of a mob spawner’s mob type within a 17x9x17 centered on the spawner block, then it will not create more until the current mobs move away, die or despawn.

Monster spawners are normally inactive. They do not create mobs unless there is a player within 17 blocks of them. Mobs will start to appear in an 8x3x8 area centered on the spawner block as long as a player is in range. Every 10 to 40 seconds (200 to 799 ticks), mob spawners target 4 random blocks in the surrounding 8x3x8 area and try to spawn mobs there. It will keep trying to spawn monsters every few seconds until at least 1 appears, then it will start the countdown again.

Comments are closed.