Spawn

This article needs to be updated.

Please update this page to reflect recent updates or newly available information.
Reason: A comprehensive check that this article is up-to-date from 1.9 to 1.18 is in order.

Spawning refers to the creation and placement of players and mobs in the Minecraft world.

Player spawning

World spawn

Spawning Area — World spawning area. White represents the extent of singleplayer, blue represents multiplayer, and yellow represents the world spawn point.

New players initially spawn within a small area surrounding the world spawn point when the server is not in Adventure mode. This area is 21×21 blocks by default, but can be changed by the spawnRadius gamerule in both single and multiplayer. Upon death or return from the End dimension, the player respawns within this area unless the player's individual spawn point changed (by using a bed or respawn anchor, or the /spawnpoint command).

When the player first loads into the world or respawns, the game searches within the world spawn area and tries to place the player on a random grass block. Upon spawning, the player is placed on the highest valid spawn point block of the X and Z spawn coordinates, even if this would set the player above the maximum build height. However, if there are no valid spawn points but a grass block that was determined to be an invalid spawn point due to being blocked by a block above it (though the grass block would decay soon after), the game checks the closest two free spaces from below and the player spawns there. If there are absolutely no grass blocks, the player spawns directly at the world spawn point, which can even result in players spawning above the Void if there are no blocks at that location.

The world spawn point also determines the center of the permanently loaded spawn chunks.

The world spawn point itself can be changed using the /setworldspawn command.

Bedrock world spawn search

This section needs to be updated.

Please update this section to reflect recent updates or newly available information.
Reason: Spawn search rules have changed in 1.18; more biomes are available to spawn in.

In Bedrock Edition, when a player creates a new world, the world spawn point is restricted to specific biomes. The algorithm starts searching from coordinate 0,0, continuing outward until an acceptable biome is found for the world spawn point. Using add-ons, a rare biome can be designated to cause the player to spawn at a distant location, but the game crashes if the biome does not exist or cannot generate.

The algorithm searches for these biomes:

Plains
- At main plains biome
- Small islands in an ocean (islands are usually a plains biome)
- Patch of plains next to desert, badlands, or snowy plains
Forest
- At main forest biome
- Small islands in an ocean (islands can also be a forest biome)
Dark Forest
Taiga
- At main taiga biome
- Patch of taiga next to old growth pine taiga
- Near beach, snowy taiga, or windswept hills
Jungle
Savanna (only regular variants)

The player spawns within a 5-block radius of the point selected in the chosen biome, sometimes resulting in the player spawning outside the intended spawn biome, ending up in a beach, river, or swamp biome. It is also possible (but rare) for a player to spawn initially underwater and start drowning.^[1]

A search for a valid world spawn biome is not performed for Flat and Old world-types.

Adventure mode

When the server's settings specify the default game mode as Adventure (using the server.properties), then the normal spawning mechanic is ignored, and players are spawned directly on the world spawn point. This includes the X, Y, and Z coordinates, even if there is no block there, and even if there are blocks above it.

If the Y coordinate is not within a valid spawning area, then the server looks up until it finds one, up to a maximum of Y=256. If there is space to spawn, but it is in mid-air, the player spawns in mid-air, even falling into the Void if there is a hole.

Location

There are several ways to determine the world spawn point:

A compass (that hasn't been assigned to a lodestone) always points to the world spawn point.
Doing the commands /gamerule spawnRadius 0 then /kill.
If commands are disabled, remove all the grass blocks in the 21×21 spawn area (or place a block above them to make them invalid), make sure the individual spawn point is disabled, and die.
Entities, other than players, falling into the exit portal in the End land exactly at the world spawn point. Items thrown in mark the spot in the Overworld. Players spawn like they normally do, allowing this action to be used to perform the above without dying, and thus can be performed in hardcore mode.
Mods or external programs, such as NBTExplorer or MCEdit, can also be used to find and set the world spawn point.

Individual spawn

The individual spawn point of the player can be changed by sleeping in a bed, using a respawn anchor, or using the /setworldspawn or /spawnpoint command. If the individual spawning area of the player is obstructed upon death, the player respawns at the world spawn.

Sleeping in a bed allows for leniency in obstruction, in that the player respawns on other blocks near the bed if the original point becomes blocked. The same is true for the respawn anchor. If the spawn point set via /setworldspawn or /spawnpoint becomes obstructed, the player is not given this leniency in respawning.

Natural generation

Animals

CowInATree — A cow that generated with the map inside a tree's leaves and could not escape, a common sight in forested hill areas.

In Java Edition many animals generate upon initial chunk creation. These spawns occur only once per chunk. They are not affected by the /gamerule doMobSpawning command.

One in ten newly-generated chunks attempts to generate animal mobs, usually in packs of up to 4 of the same species. The spawn attempt always starts on top of the highest available block in a randomly chosen column within the chunk. The chosen position must not be a solid block for the animals to generate. Once the starting position is chosen for a chunk, a second position is chosen in a 9×9 block area around the starting position. Blocks toward the center of the 9x9 area are more likely to be chosen than blocks toward the edge. The block does not need to be a grass block nor does it need to be illuminated as it does with mob spawning. If an animal can spawn at the second position, it does so. The second position becomes the first position, and a new second position is chosen like before in a 9x9 area. This process can repeat until each chunk has attempted to spawn 1–4 mobs.

In Bedrock Edition animals do not spawn during chunk generation, but they continually attempt to spawn everywhere as part of the environmental spawning algorithm, according to their spawn weights, biome tags, and block requirements (see Bedrock Edition under Spawn Cycle, below).

There are 2 types of animals: common animals and biome-specific animals.

Common animals

Common animal mobs do not spawn in desert, badlands, beach, snowy plains, river, ocean, or mushroom fields biomes.

Mobs	Weight	Group size
Sheep	6	4
Chicken	5	4
Pig	5	4
Cow	4	4

Biome-specific animals

Some animal mobs spawn only in specific biomes.^{[more information needed]}

Mobs	Biome	Weight
Axolotl	Lush Caves	4
Cod	Ocean Lukewarm Ocean Cold Ocean Frozen Ocean	75
Dolphin	Ocean Warm Ocean Lukewarm Ocean Cold Ocean	7
Donkey	Plains	1
Fox	Taiga Snowy Taiga Old Growth Pine Taiga	8
Glow Squid	Ocean^{[more information needed]}	2-4
Goat	Frozen Peaks Jagged Peaks Snowy Slopes	3
Hoglin‌^{[BE only]}	Crimson Forest	20
Horse	Savanna Plains	4 in plains 1 in savanna
Llama	Savanna Windswept Hills	8 in savanna 5 in windswept hills
Mooshroom	Mushroom Fields	8
Ocelot Parrot	Jungle Bamboo Jungle	30 for ocelots 40 for parrots
Panda	Jungle Bamboo Jungle	10 in regular jungle 40 in bamboo jungle
Polar Bear	Snowy Plains Frozen Ocean Frozen River	1 (5 in Frozen Oceans)
Pufferfish Tropical Fish	Warm Ocean Lukewarm Ocean Deep Lukewarm Ocean	25 for pufferfish 75 for tropical fish
Rabbit	Desert Taiga Old Growth Pine Taiga Snowy Taiga Snowy Plains Frozen Ocean Frozen River Snowy Beach Legacy Frozen Ocean Flower Forest	4 (20 in flower forests)
Salmon	River Cold Ocean Frozen Ocean Lukewarm Ocean	26 in oceans 16 in rivers
Squid	Ocean River	8
Strider	Nether Wastes Crimson Forest Soul Sand Valley Basalt Deltas Warped Forest	20
Turtle	Beach	8
Wolf	Taiga (all variants) Forest (all variants) Windswept Hills (all variants)	8 in taigas 5 in forests and windswept hills

Randomness for animal spawning is derived from the world seed, which means that worlds with the same seed always generate chunks with the same animals in the same places.

Monsters

Monsters cannot spawn when the difficulty is set to Peaceful (except piglin‌^{[BE only]} and hoglin). At any higher setting they spawn when block light level is 0. The player cannot sleep when a monster (other than hoglin; and in Java Edition, also include slime, magma cube and non-hostile zombified piglin) is nearby, even if the monster has no path to the player.

Common monsters

Common monster mobs can spawn in almost any biome in the Overworld (except for mushroom fields). They can spawn on the surface and underground. The weight determines the spawn rate in the Bedrock Codebase.

Mobs	Weight	Group size
Zombie	100	2-4
Creeper	100	Individually
Skeleton	80	1-2
Spider	100	Individually
Enderman	10	1-2
Witch	5	Individually
Spider Jockey	1	Individually
Chicken Jockey	0.25	Individually

Biome-specific monsters

Some monsters spawn only in specific biomes.

Mobs	Biome
Drowned	Ocean (all variants) River (all variants) Dripstone Caves
Ghast	Nether Wastes Soul Sand Valley Basalt Deltas
Hoglin‌^{[JE only]}	Crimson Forest
Husk	Desert (all variants)
Magma Cube	Nether Wastes Basalt Deltas
Slime	Swamp
Stray	Snowy Plains Ice Spikes Frozen River Frozen Ocean (all variants)
Piglin Zombified Piglin Zombified Chicken Jockey	Nether Wastes Crimson Forest

Other mobs

In Java Edition these mobs still spawn if the /gamerule doMobSpawning command is set to false, because they spawn as part of structure generation. In Bedrock Edition nothing spawns if the /gamerule doMobSpawning command is set to false.

Animal mobs

Mob	Structure generation
Black Cat	A single cat spawn within a Swamp Hut upon generation.
Cat Cow Horse Pig Sheep	Generate as part of the Village generation. Specific animals spawn as part of specific village structures: Animal pens (cow, sheep, pig, or horse), stables (horse, cow, or pig), butcher's houses (pig, cow, or sheep), and shepherd's houses (sheep).

Monster mobs

Mob	Structure generation
Drowned	Generate as part of some underwater ruins.‌^{[JE only]}
Elder Guardian Guardian	Generate as part of a single Ocean Monument.
Ender Dragon	Created in The End when the dimension is created. The ender dragon can also be respawned by placing end crystals on the exit portal.
Evoker Vindicator	Generate as part of woodland mansion.
Pillager	Spawn from pillager outposts.
Shulker	Generate as part of end cities.
Witch	A single witch spawn within a Swamp Hut upon generation.
Zombie Villager	Generate as a part of an igloo if it generates with a basement. Can spawn as part of zombie village generation, where they never despawn naturally.

Other mobs

Mob	Structure generation
Iron Golem	Spawn from pillager outposts.
Iron Golem Villager	Generate as part of the village generation. Each villager spawns in a house with a bed, and an iron golem spawns as part of meeting points.
Villager	Generate as a part of an igloo if it generates with a basement. Can spawn as part of zombie village generation, where they never despawn naturally.

Spawn cycle

Java Edition

Mobs are broadly divided into seven categories: hostile, friendly, water creature (squids and dolphins), underground water creature (glow squids), axolotls, water ambient (all 4 types of fish), and ambient (bat). Hostile and water mobs have a spawning cycle once every game tick (¹⁄₂₀ of a second). Friendly mobs have only one spawning cycle every 400 game ticks (20 seconds). Because of this, where conditions permit, hostile mobs spawn frequently, but passive mobs (animals) spawn rarely. Most animals spawn within chunks when they are generated.

Mobs spawn naturally within a square group of chunks centered on the player, 15×15 chunks (240×240 blocks). When there are multiple players, mobs can spawn within the given distance of any of them. However, hostile mobs (and some others) that move farther than 128 blocks from the nearest player despawn instantly, so the mob spawning area is more-or-less limited to spheres with a radius of 128 blocks, centered at each player. In multiplayer, mob caps are shared by all players, no matter where they are.

Every 24000 game ticks (20 minutes) the game attempts to spawn a single wandering trader with two leashed llamas within 48 blocks of a player or at a village meeting place, if no wandering trader exists in all loaded chunks. The trader does not spawn when the player is underground.‌‌^{[Java Edition only]}

Java Edition mob cap

This section needs expansion.

You can help by expanding it.
Instructions: The new charge/cost/energy system used for Soul Sand Valleys and Warped Forests. Each mob has a cost for spawning and deducts it from the biome's total energy. Is it reduced per entity spawn or per pack spawn? How does energy recharge? Etc. See Biome.java, NaturalSpawner.java, and PotentialCalculator.java.

Mob caps are directly proportional to the total number of chunks eligible for spawning. To calculate the cap, the spawning area is expanded by one chunk in every direction (so the default gives 17×17 chunks), then the total number of chunks is plugged into the following formula:

mobCap = constant × chunks ÷ 289

The constants for each group are as follows:

Monster = 70
Creature = 10
Ambient (bats) = 15
Axolotls = 5
Underground water creature (glow squids) = 5
Water creature (squids, dolphins) = 5
Water ambient (fish) = 20
Misc = -1

The "misc" category is used only by entities that are not mobs, do not spawn naturally, and/or following different spawning rules than other mobs. As such the mob cap has no bearing on mobs of this category.

In singleplayer, there are always 289 chunks in range, so the constant is always used as the global mobcap.

In multiplayer, the global mob cap grows as more chunks are loaded. Because chunks that are in the range of multiple players are counted once, more chunks and higher mob caps result from the players spreading out.

The number of mobs is checked once per each chunk against the cap. If the number of mobs (dead or alive) in a category is at its cap, the entire spawning cycle for that category is skipped. The area checked for mobs is the same as the area used for calculating the mobcap, which is the spawning area expanded by one chunk in every direction. The mobcap count is separate for each dimension.

Every chunk, the game checks the mobcap. As such, you can reach mobcap+pack size from natural spawns.

When /gamerule spectatorsgeneratechunks is set to false, spectators do not raise mobcap.

Pack spawning

Spawning science — Example of a mob pack spawning. The 41×1×41 spawning area is shaded blue (not to scale). The yellow figures represent the actual positions that mobs could spawn in after checking the environment. Note that the mobs can spawn inside torch and ladder blocks. But they can't spawn on top of glass because it is not opaque. The red cube is the center of the pack.

Spawning requirements — Requirements for the spawning location of individual mobs.

For each spawning cycle, attempts are made to spawn packs of mobs per each eligible chunk. An eligible chunk is determined by the same check for which chunks are random ticked. A random location in the chunk is chosen to be the center point of the pack. If the block in which a pack spawn occurs is an opaque full cube, further pack spawn attempts are canceled. There are a maximum of 3 pack spawn attempts per mob category.

The pack is spawned within a 41×1×41 (that's a 41×41 square that is one block high) area centered at the initial block. Mobs spawn with the lowest part of their body inside this area. For each spawn attempt, from the location of the previous attempt, a location up to 4 blocks away from the previous attempt is chosen at random. Thus, the spawns are heavily skewed toward the center of the pack. Approximately 85% of spawns are within 5 blocks of the pack center, and 99% within 10 blocks of the center. If the pack spawn enters a biome different from the starting biome, the rest of the pack and that spawn are canceled.

All mobs within a pack are the same species. The species for the entire pack is chosen randomly, but based on a weight system from those eligible to spawn at the location of the first spawn attempt in the pack.

The game checks on each spawn if the number of mobs that have been spawned for the pack is equal to the max spawn attempts, as well as the location's spawn potential.

Pack spawn size

Pack spawn attempts max out at:

8 Wolves, cod, and tropical fish
6 Horses and Donkeys
1 Ghast
4 for any other mob

When the max pack size is less than the number of possible spawn attempts, some spawns attempts fail, but are seen more commonly in practice. Based on the number of mobs that have been successfully spawned. If the max pack size is greater than the number of spawn attempts, one gets only the number of spawns from the spawn attempts. Some mobs have a minimum and max pack size, meaning there is an even chance for any number of spawn attempts between them occurring.

For zombie villagers, drowned, pillagers, donkeys in savanna biomes, parrots in jungles excluding bamboo jungle and jungle, cats in swamp huts and witches, it is 1.
For parrots in bamboo jungles and Jungle, polar bears, squids in lukewarm oceans, pandas and dolphins, it is 1-2.
For donkeys in plains biomes, ocelots and pufferfish, it is 1-3.
For endermen except in the End and in nether wastes, and squids except in lukewarm oceans, it is 1-4.
For rabbits and blazes, it is 2-3.
For guardians, foxes, zombified piglins in crimson forests and striders, it is 2-4.
For turtles, it is 2-5.
For horses, it is 2-6.
For piglins and hoglins in crimson forests, it is 3-4.
For Cod it is 3-6.
For llamas, it is 4-6.
For mooshrooms, it is 4-8.
For wither skeletons and skeletons, in nether fortresses, it is 5.
For bats and tropical fish, it is 8.
For every other mob, it is 4.

Pack spawn location

For all dimensions, structure-based spawns take priority over biome for hostile spawns. This means that in a swamp hut, pillager outpost, nether fortress (outer bounding box only when there is nether bricks below it‌^{[JE only]}), and ocean monument, one sees only the corresponding hostile mobs for that structure within that structure.

In the Overworld, this depends on the location:

Jungle biomes have a higher chance to spawn chickens.‌^{[Java Edition only]}
Badlands biomes spawn only hostile mobs and bats.
River and frozen river can spawn only drowned, squid, and salmon underwater.
Ocean biomes do not spawn passive mobs. They spawn drowned, and the other hostile mobs. Frozen oceans do not spawn dolphins, but do spawn polar bears.
Snowy Plains biomes do not spawn animals other than polar bears and rabbits.
Swamp huts spawn only witches, cats, and bats.
Ocean monuments spawn guardians, other water mobs and bats.
Pillager outposts spawn pillagers, other passive mobs and bats.
All other overworld biomes spawns common animals and common monsters, as well as slimes, dependent on spawn conditions.

In the Nether:

Skeletons, wither skeletons, magma cubes, zombified piglins, and blazes spawn within nether fortresses.
Ghasts spawn in nether wastes, soul sand valley and basalt deltas.
Zombified piglins and piglins can spawn in nether wastes, while magma cubes spawn primarily in basalt deltas and sometimes in nether wastes.
Ghasts, magma cubes and hoglins spawn regardless of light level.
Hoglins and piglins spawn at a higher rate anywhere in the crimson forest biome.
Endermen spawn more frequently in the warped forest biome, but not in the crimson forest.
Skeletons and ghasts spawn more frequently in the soul sand valley biome.

Spawn conditions

Whether a spawn condition fails differs from the above determination if the game tries to spawn them in that biome. For example, dolphins can have pack spawns that occur inside of frozen ocean and deep frozen ocean biomes, but no other biomes. These rules apply to variants of the same mob, such as baby zombies and spider jockeys.

Each individual spawn attempt succeeds only if all of the following conditions are met:

There must be no players or the world spawn point within a 24 radius block distance (spherical) of the spawning block
The number of loaded mobs of that type must be less than the mob cap for that type. (I.e. the corresponding mobcap must not be full)
The mob's collision box upon spawning must not collide with another collision box. A mob cannot spawn inside of anything that would collide with it upon spawning.
The mob's collision box must not intersect with a solid block.
For all mob types excluding passives and fish, spawns fail unless within a 128 radius block sphere around the player. For fish, spawns fail unless within a 64 block radius of the player. ^[2]
/gamerule doMobSpawning is true
For non-aquatic mobs, the spawning block and the block above that cannot be rails, powered rails, detector rails, activator rails, redstone components, wither roses (except for wither skeletons) or sweet berry bushes (except for foxes).

Hostile mobs

The difficulty must not be Peaceful, excluding piglins and hoglins
This also affects ocelots^[3]
For all hostiles other than guardians, drowned, and phantoms:
- the block directly below it must have a solid, opaque, top surface (this includes upside down slabs, upside down stairs, and others) or be soul sand or a slime block.
- the block directly below it must not be bedrock, barrier, or‌ any type of trapdoor‌ or glass.
- The mob's collision box must not collide with any liquid.
- The block above the spawning block must be transparent
For slimes from swamp biomes, creepers, skeletons, wither skeletons, witches, zombie villagers, husks, strays, drowned and spiders:
- The light level divided by 8 is the chance of a spawn failing; thus mobs spawn at light level 7 and below.
  - In the Overworld, this follows internal skylight level as well as block light level. Internal light level is affected by thunderstorms.
- Spawns with sky access in the Overworld have an additional 50% failure rate when the light level is 15.
- If it is a slime from a swamp biome, then.....
  - the spawning block must be in a swamp biome
  - the spawning block be on level 51 through 69 inclusive
  - chance of failure based on the phase of the moon
  - with a 50% chance of failure.
- If it is a husk or stray, then....
  - The location of the spawn must have sky access.
- If it is a skeleton in a Nether fortress, then...
  - There is an 80% chance of spawning a wither skeleton instead.
- The light checks in the general hostile mob check don't apply to:
  - Slimes from slime chunks (see the slime page for details), which spawn when:
    - the spawning block is below level 40.
    - with a 90% chance of failure.
  - If it is a ghast, then...
    - With a 95% chance of spawn failure.
  - If it is a magma cube or hoglin, then...
    - the block below must not be a nether wart block.
  - If it is a blaze, then...
    - the light level must be 11 or darker.
  - If it is a piglin or zombified piglin, then...
    - the light level must be 11 or darker.
    - the block below must not be a nether wart block
  - If it is a polar bear, then...
    - The light level must be greater than 8.
    - The block beneath must be ice.
    - The spawning block must be in a frozen ocean or deep frozen ocean.
  - If it is a blaze, wither skeleton, skeleton, magma cube or zombified piglin in the fortress external bounding box:
    - the block beneath must be nether bricks.
  - If it is an ocelot, then.....
    - the spawning block must be level 62 or higher.
    - the block directly below the spawning block must be grass or leaves.
    - there is a ¹⁄₃ chance for the spawn to fail in jungles, 100% chance in bamboo jungles and jungle edges.
For guardians and drowned:
- The spawning block and the block below must be water, including waterlogged blocks and bubble columns.
  - If it is a guardian, then...
    - 95% chance of failure if the spawning block has sky exposure (details).
  - If it is a drowned:
    - It has a ¹⁄₄₀ chance to succeed in oceans, while a ¹⁄₁₅ chance to succeed in rivers.
    - In ocean biomes, drowned spawn at a height less than 5 blocks below sea level.

Passive mobs

The mob's collision box must not collide with any liquid.
- if it is not a strider, the light level of the spawning block must be 9 or brighter.
  - If it is a mooshroom, then.....
    - the block directly below the spawning block must be mycelium.
  - If it is a turtle, then.....
    - the block directly below the spawning block must be sand.
    - the spawning block must be level 67 or lower.
  - If it is a ocelot, then....
    - Spawn has a 33% chance of failure.
    - the block directly below the spawning block can either be grass block or leaves.
  - If it is a parrot, then....
    - the block directly below the spawning block can either be grass block, leaves, or log.
  - If it is a rabbit, then....
    - the block directly below the spawning block must either be grass block, snow^[4], or sand.
  - For all others then.....
    - the block directly below the spawning block must be a grass block.
- If it is a strider, then.....
  - Spawn attempts with lava above check upward as long as there is still lava for if they can successfully spawn in a lava block with air on top.
  - The spawning block must be at y level 31 or lower.

Aquatic mobs

For squid, cod, salmon, pufferfish, tropical fish or dolphin:

the spawning block and the block below must be water
the block above must be water and cannot be waterlogged
- If it is cod, salmon, pufferfish, tropical fish, then the water ambient mobcap must not be full
- If it is squid or dolphin, the water creature mobcap must not be full
- *If it is a squid, then...
  - - the spawning block must be between level 46 and 62, inclusive
    - the spawning block must be in an ocean or river
  - If it is a dolphin then.....
    - the height of the spawn must be greater than 45 and less than sea level (62).
    - the spawning block must be in an ocean or deep ocean

Ambient mobs

The mob's collision box must not collide with any liquid.
- If it is a bat, then...
  - the spawning block must be at level 62 or below.
  - If the real-time day is between October 20 and November 3, then the light level must be 7 or darker. Otherwise, the light level must be 4 or darker.

If all of these conditions are met then the mob is spawned.

Spawn costs

Spawning potential as visualized with minecraft — Locations that do not have spawning potential reliant spawns are marked by wart blocks or netherrack

Endermen within warped forests, and skeletons, ghasts, striders and endermen in soul sand valleys increase a charge within the spawn cost. If the charge is high enough in an area, any mob that adds to the charge does not spawn.

Charge raising mobs add the charge in a sphere around them. This occurs farther the charge cancels spawns. Mobs' charge spheres don't cover each others' up, but stack, affecting areas further away, given the mobs are in proximity. The charge set by 1 mob is the same throughout the block the mobs resides in and the block south, east, and southeast adjacent to it. From that, charge prevents spawns within 6 blocks straight between them or 4 blocks along a diagonal, given no other charge affecting mobs are present.

Due to the spawning suppression in soul sand valleys and warped forests, a larger-than-usual amount of mobs spawn in any space outside of these biomes, including in Nether fortresses.

Notes

Buildings surrounded by air spawn more mobs inside than underground rooms because packs that spawn outside of the building can spawn mobs inside it. The mob caps tend to be reached in seconds.
If the player's view distance or the server view distance in multiplayer is at 9 or below, mob spawning is severely reduced (or they despawn too quickly), and may result in the player encountering no mobs at all. Set the view distance to 10 or higher to ensure mobs spawn correctly.

Bedrock Edition

Environmental spawning in Bedrock Edition shares broad similarities to natural spawning in Java Edition: mobs spawn in a radius around the player subject to block conditions, lighting conditions, biome conditions, naturally generated structure conditions, and caps. Many mobs spawn in groups (called "packs" in Java and "herds" in Bedrock). One notable difference from Java Edition is that most animals can spawn at light level 7 or higher rather than 9 or higher.

There are two types of environmental spawns: cluster spawns and structure spawns. Structure spawns reproduce specific types of mobs at specific locations within certain naturally generated structures, such as nether fortresses, swamp huts, etc. Cluster spawns account for all other types of environmental spawns, including mobs that spawn individually (i.e. not in a herd of 2 or more). Both types of environmental spawns follow the same rules for spawn conditions and mob caps, except that structure spawns can exceed the monster population cap by 1 (see below).

Mob spawning in bedrock edition happens within a spherical shell 24-44 blocks away from the player on simulation distance 4. It happens a quasi-spherical shell 24-128 blocks away from the player, restricted by a simulation distance and/or to roughly 96 blocks horizontally, on simulation distances 6 and higher. This means that mobs can spawn directly above or below the player (for example, phantoms in the sky or zombies underground). Mobs can spawn only in chunks that are being ticked. There is a ¹¹⁄₂₀₀₀ chance of the mob spawning algorithm attempting to run per chunk, per tick.

Bedrock Edition mob cap

There are three mob caps that affect environmental spawning: a global mob cap, population control caps for general mob types, and density caps for specific mob types. The global mob cap is set at 200 regardless of difficulty. The global mob cap affects only environmental mob spawning, and does not affect mobs spawned through breeding, spawn eggs, the /summon command, spawners, or any other type of mob spawning. Chickens created by thrown or dispensed eggs are counted in the global mob cap. Only mobs that have spawn rules count toward the global cap (i.e. armor stands and minecarts do not take up cap space). In addition, mobs that are within ticking areas (both those around players and those set manually using the /tickingarea command) count toward the global mob cap; mobs not ticked do not count toward the global mob cap.

The population control caps limit how many mobs of each type and category can spawn within a 9 chunk by 9 chunk square region surrounding the chunk in which the spawn attempt is made. Mobs in chunks outside a ticking area still count toward population control counts as long as they were previously loaded (i.e. within simulation distance at some time) after relogging. The population control caps are split up into two distinct categories: a cap for surface mobs, and a cap for cave mobs. Cave mobs do not count toward the surface mob cap, and surface mobs do not count toward the cave mob cap. Whether a mob counts as a surface mob or a cave mob is determined by where or how it spawned, not where it happens to be at the moment. For cluster spawns, those that spawn on the highest spawnable block at a given coordinate count toward the surface cap, and any that spawn below the highest solid or non-solid but spawnable (e.g. ice or upper slab with air above) block count toward the cave cap. Structure-spawned mobs and converted mobs (i.e. drowned converted from zombies, witches from villagers, zombified piglins from pigs, and medium and small slimes from killed larger slimes) always count toward the cave cap, and spawner-spawned mobs always count toward the surface cap.

There are five categories of mobs: ambient, animal, monster, pillager, and water_animal. The population control cap for each category and location of mob in each dimension is as follows (* denotes values that are coded in the game but not actually used by any mobs):

Population control caps
Category	Location	Overworld	Nether	The End
Ambient	Surface	0	0	0
Ambient	Cave	2	0	2*
Animal	Surface	4	0	4*
Animal	Cave	0	4	0
Monster	Surface	8	0	10
Monster	Cave	8	16	8*
Pillager	Surface	8	0	8*
Pillager	Cave	8	0	8*
Water_Animal	Surface	36	0	36*
Water_Animal	Cave	0	0	0

Some specific mobs types also have their own density caps. The density caps limit the number of those mobs to some amount below the applicable population control cap. Density caps are checked in the same manner as the population control caps. Caps are below (n/a indicates that the mob does not spawn in that environment at all).

Mob Density Caps
Mob	Surface cap	Cave cap
Cod	20	n/a
Creeper	5	unlimited (population control cap still applies)
Dolphin	5	n/a
Drowned	5 in ocean 2 in river	n/a
Ghast	n/a	2
Phantom	5	n/a
Pufferfish	3	n/a
Salmon	10 in ocean 4 in river	n/a
Squid	4 in ocean 2 in river	n/a
Tropical Fish	20 for preset pattern 20 for random pattern	n/a

Bedrock spawn conditions

The following rules apply to most mobs:

Mobs spawn at a distance from the player that depends on the world's simulation distance:
- Simulation distance 4: between 24 and 44 blocks spherical radius from the player.
- Simulation distance 6 and up: between 24 and 128 blocks spherical radius from the player, but limited horizontally by simulation distance and coding that restricts the spawning algorithm from running in chunks whose center exceeds 96 blocks from the player.^[5]
The bottom part of the mob (i.e. the feet of a standing mob, or the whole body of a mob <= 1 block tall) can spawn only in an air block, or for water mobs in a water block. A few naturally-generated, non-motion-blocking blocks such as grass and flowers are ignored for this rule.
There must be a block with a full, solid top surface under the spawn location for the mob to spawn on. (I.e. mobs cannot spawn on carpets, lower slabs, fences, right-side-up stairs, redstone repeaters, chests, etc.)
Mobs cannot spawn on transparent full blocks like glass and leaves.
For mobs that can spawn floating in water or flying in air, the block that is checked for spawning is the water or air block immediately above the first solid top surface block below the spot where the mob would spawn. (So for example, phantoms cannot spawn over a field covered in carpet, and fish cannot spawn in an ocean where bottom slabs cover the ocean floor.)
Most overworld monsters cannot spawn if the sky light level is greater than or equal to 7 or the block light level is greater than 0.
Most overworld animals cannot spawn if the (combined) light level is less than 7.

Cluster spawning

Cluster spawning happens in two stages: first attempt to spawn surface mobs, then attempt to spawn cave mobs. Before spawning, the population control cap is calculated based on the 9 chunk x 9 chunk square area surrounding the current chunk. Spawning begins by picking a random X and Z location within the chunk currently being evaluated. The Y coordinate is determined by starting at the world height and searching downward for a solid-top-surface block with a non-spawn-blocking block above it. The first such block that is found is considered to be the surface, and the algorithm attempts to spawn a surface mob herd. However, if the algorithm finds a solid block before finding a spawnable solid-top-block (e.g. if it finds a tree trunk directly under leaves), it does not make any surface spawn attempt. The algorithm then continues to search downward for the next suitable block with a non-spawn-blocking block above it. When a block meeting the criteria is found, the algorithm attempts to spawn a cave mob herd at that block location. Cave spawn attempts continue until the Y coordinate reaches the world bottom, and do not stop even if a cave herd was spawned.

Surface and cave cluster spawn attempts then go through the following steps to figure out what mob to spawn and how many:

Picks a random mob.
- If the current spawn location is in a liquid, pick a random water mob.
- If the light level is 7 or higher, there are no other blocks above the current location, and the current location is a grass block, pick a random animal mob.
- Otherwise, spawn a monster mob.
Picks a random number of mobs to spawn in the herd. Each mob can have its own min and max herd size, and the herd size can depend on difficulty and biome.
Make sure the spawn location has suitable spawn conditions.
Limit the number of mobs spawning based on the global mob cap. No mobs spawn if the mob count already meets or exceeds the mob cap.
For each mob to spawn, check that spawning it would not exceed the population control cap or mob density cap.
- If spawning the mob would not exceed the population control or mob density caps, then the probability of a mob spawning can be calculated using the formula: (mob density cap - current mob density count) / mob density cap
Finally, attempt to spawn the mob in the world.
- Spawning the mob can fail; for example, if spawning it would cause it to spawn inside of a block or part of a wall.

Structure spawning

Structure spawn attempts occur at specific relative X and Z coordinates in naturally generated structures, known as "hard-coded spawn spots". The structures that have hard-coded spawn spots include swamp huts, ocean monuments, pillager outposts, and nether fortresses. Whenever a successful cluster spawn attempt occurs within a chunk that contains a hard-coded spawn spot, the environmental spawning algorithm also attempts a structure spawn. (Note that a "successful attempt" here means that a spawnable block was found, even if the spawn was then blocked by light level check or mob cap check.) The structure spawn attempt follows the same rules and steps described above for cluster spawning, with the following changes:

Instead of starting at world height and searching down to bedrock at the specific X and Z location, the search begins and ends at a specific Y values determined by the type of structure. Structure spawn attempts occur only on the first spawnable block found (i.e. the highest spawnable block) within that range.
The mob picked depends on the structure: swamp huts spawn witches, ocean monuments spawn guardians, pillager outposts spawn pillagers (including patrol captains), and nether fortresses spawn skeletons, wither skeletons, blazes, and magma cubes.
The population control caps are effectively 1 higher for structure spawn attempts.

Other types of spawning