Levels 0 through 39 in specific chunks, any light level
A slime is a hostile mob in the shape of a green cube in various sizes. They are able to see the player through solid blocks, and will always try to move directly toward players without regard for obstacles or hazards. When killed, a slime will split into smaller slimes. When those slimes are killed, they will drop slimeballs.
In Minecraft, only sizes 1, 2, and 4 spawn naturally, and with equal probability. With use of
/summon, slimes can potentially range from size 1 to 256.
Slimes move by hopping, which they will do each 10 to 30 ticks (1⁄2 to 1 1⁄2 seconds). Their exact routine is as follows:
The Slime will search for a player within 16 blocks (spherical) distance.
- If no players are found, they wait 10 to 30 ticks (1⁄2 to 1 1⁄2 seconds). Then they will change direction, by a random amount up to 57.26° (1 radian) left or right, jump, and repeat the process.
- If a player is found, the delay before jumping will be 1⁄3 as long (3 to 10 ticks), and the Slime's direction will be set directly toward the nearest player before jumping.
A slime's health is equal to their size squared, and its dimensions are 0.6 blocks times its size in each dimension. When a slime attacks, it will deal damage equal to its size, except for size 1 (smallest) slimes, which cannot do damage.
When the player kills a slime and the slime's size is larger than 1, it will die and spawn 2-4 new slimes equivalent to its size divided by 2, rounding down.
If the slime's size is 1, it will drop 0-2 slimeballs. If it is larger, it will only drop experience. All slimes drop experience equal to their size. The slime balls can be used for many different crafting recipes such as sticky pistons, leads, and slime blocks.
In swamps, slimes may spawn at night between the heights of 50 and 70 provided the light level is 8 or less. They spawn most often on a full moon, and never on a new moon. This can make gathering slimeballs difficult, as it takes over two hours for the moon to completely cycle.
More precisely, the game checks if the light level is equal to or less than a random integer (from 0 to 8), then if the fraction of the moon which is bright is greater than a random number (from 0 to 1). If these conditions are met and the altitude is acceptable, there is a 50% chance of spawning a slime.
 Low layers
Slimes spawn throughout the world (except mushroom islands) below layer 40, but only in certain chunks, 1 in 10 of all chunks. However, in these chunks and layers, they spawn regardless of light level. The "slime chunks" are determined pseudo-randomly by combining their chunk coordinates with the seed of the world. Tools exist to calculate which chunks are slime chunks—see Slime finding tools.
One in 10 of chunks will be able to spawn slimes underground, based on the formula:
Random rnd = new Random(seed + (long) (xPosition * xPosition * 0x4c1906) + (long) (xPosition * 0x5ac0db) + (long) (zPosition * zPosition) * 0x4307a7L + (long) (zPosition * 0x5f24f) ^ 0x3ad8025f); return rnd.nextInt(10) == 0;
That is, using the chunk coordinates to help generate a seed, a random number between 0 and 9 will be generated, and if that number is 0, the chunk will be able to spawn slimes. To convert world coordinates to chunk coordinates, divide by 16 and round down.
Like most other mobs, Slimes require two vertical non-opaque blocks (e.g., air, signs, torches) to spawn in, with an opaque block underneath. The space they spawn in must also be clear of solid obstructions and liquids.Verify big slimes require a 3x2.5x3 space to spawn (that is, between a floor that allows spawning with a top slab over two non-opaque blocks), small slimes require a 3x2x3 space, and tiny slimes require a 1x2x1 space (or 1x1x1 if the upper block is not opaque). Slimes are equally likely to spawn at all sizes. Slimes are much more likely to spawn in a 3 high room.
Big slimes can spawn in a 2.5 high space and can move, though very slowly and noisily, in such a space (unlike Wither Skeletons, which cannot move if they spawn in such conditions).
Slimes spawn only 1/10th as often as other hostile mobs, so unless a swamp biome is nearby, they can be hard to find. Slimes in low levels can spawn in any light level and lighting does not affect their spawn rate. However, lighting up the surrounding area does decrease the chances of non-slime mobs spawning, and thus indirectly increases slime spawning rates. Glowstone has the same properties as glass, so mobs cannot spawn on it.
Like other hostile mobs, slimes will not spawn within 24 meters (spherical) of any player, and will despawn instantly if no player is within 128 meters. However, other mobs will also randomly despawn over time if no player is within a 32 meter range. In contrast, slimes will never despawn if there are players within the 128 meter range. Since 14w06a, slimes will despawn like other hostile mobs. 
Once a slime spawning chunk has been determined the process of encouraging slime spawning is relatively simple. The player can clear out large rooms - typically 3 x 3 x 3 or larger (but for maximum efficiency clear out the entire chunk - 16 x 3 x 16). It might be wise to light these rooms to prevent other hostile mobs from spawning. Waiting for slimes to spawn in these rooms can be lengthy at times, however. Killing slimes with either the use of fire or water is recommended. Water is a good method due to slimes being unable to swim. See Slime Spawning for more information on how to increase this rate.(Note that in 1.8 water will no longer work since slimes can swim, unless a downwards stream is used).
|1.0.11||Added slimes, the fifth hostile mob added to the game. There are four sizes: Tiny, Small, Big and Huge.|
|1.0.12||Big Slimes no longer spawn in peaceful.|
|Slimes have sound effects.|
|Fixed Slime targeting and attacking.|
|1.0.13||Slimes have a new look.|
|1.0.17||Slimes spawn in multiplayer.|
|1.1.2||Slime spawning reduced as they would appear in abundance. A miscalculation in the new limit caused slimes to only spawn in strange locations, so natural slime spawning was disabled.|
|1.2_01||Slimes had been reskinned and returned in Beta 1.2_01 but were still very rare. Small slimes dropped 0 - 2 slimeballs in Beta. On many old SMP servers, slimeballs were used as money, because back then there were no uses for slimeballs. Slimes also used to be extremely rare, thus making it hard to "cheat" the economy.|
|1.3||Slimes became more common.|
|1.4||SMP bug fixed where slimes split were visible only to the player that caused them to split and would not take any damage. Because these slimes were client-side, the player could only remove them by exiting and logging back into the server.|
|1.5||Slimes no longer spawn in Peaceful mode and only attack with provocation.|
|1.0.0||1.9pre5||Slimes now spawn on levels 0-39 rather than 0-16, making them much more common.|
|1.1||11w49a||Added slime spawn egg|
|1.3.1||12w15a||Decreased slime spawning rate in superflat worlds.|
|12w25a||Decreased slime spawning rate in superflat worlds even more.|
|1.4.2||12w38a||Slimes have a new mob sound, the same as Magma Cube, to make the sounds more realistic.|
|12w40a||Slimes are now easier to find as they spawn in swamp biomes at low light level. Since slimes can't swim, it's quite likely that they will jump in deep water and eventually drown.|
|1.5||13w10a||Slime spawn rates in swamps now depend on the current moon phase.|
|1.8||14w06b||Now swim as a result of the update to the new AI.|
|Randomly change direction every so often, reducing the chance of them getting stuck at walls or corners.|
|Slimes will now randomly despawn over time if no player is within a 32 meter range.|
|14w11a||Appear to jump a bit more randomly.|
|14w20a||Slime sizing was moved to a post-spawn method. Originally the slime's
|Pocket Edition Alpha|
|0.9.0||build 1||Added slimes and slime spawn egg.|
|build 2||Slimes now have sounds.|
|TU14||Decreased slime spawning rate in superflat worlds.|
 Pre-1.4 spawning
The (pre-1.4) slime spawning algorithm is discussed in greater detail in this forum topic, but note that the algorithm has changed many times and older information may no longer be accurate.
 Slime finding tools
- Rei's Minimap (Mod) Able to highlight slime chunks in a singleplayer game.
- What's My Light Level (External) Can also aid players in finding slimes.
- Minecraft X-Ray (External) Shows slime chunks since version 3.4.0
- AMIDST (External) Finds slime chunks as well as Strongholds, Villages, and Biomes.
- Slimes may have been inspired by a number of classic gaming monsters. Their shape and size resemble that of Gelatinous Cubes from Dungeons & Dragons (though admittedly that comes more from Minecraft's cubic art design), while their splitting behavior resembles that of Zols and Chuchus from The Legend of Zelda, Puddings from Nethack and Amoeboids from Ratchet and Clank. The name and the large, cartoonish face may be a homage to Yuji Horii's iconic Slimes from the Dragon Quest series.
- Slimes do not prevent you from sleeping.
- Tiny slimes have the least amount of health of any mob in the game, with only 1 (). Because of this some players refuse to waste sword durability on small slimes, preferring to use an empty hand or a block.
- Because there is a limit on the number of hostile mobs that can exist in all the loaded chunks at once, splitting several slimes into tiny slimes and letting them follow the player will greatly reduce the chances of encountering other monsters.
- Slimes will only attack the player, even if a skeleton accidentally shoots it.
- Part of the slime coding allows tiny slimes to spawn on Peaceful, but the natural spawning algorithm skips hostile spawning entirely on Peaceful. As a result, tiny slimes cannot spawn. However, there are illegitimate ways to spawn the slimes on Peaceful, e.g. with a slime Monster Spawner.
- Slimes hop much faster when pursuing a player.
- Despite Slimes being hostile mobs, many players have tiny Slimes as pets since they follow and can't directly damage players.
- From one large slime, the maximum experience a player can get from killing it and all the slimes that split from it is 28 XP; 4 XP from the largest, 8 XP from the 4 it splits into, and 16 XP from the 4 each of those split into.
- One-block ceilings of opaque blocks immediately below slimes will have a green "leak" particle effect (as with lava and water).
- To calculate the health of a slime, the formula is
health = size2.
- The new Slime Block in 14w02a has a similar texture to the outside of a slime.
A pack of slimes but the NPC Village is still there
 See also
- Magma Cube – a similar entity that spawns only in the Nether