How Slime Chunks Work and How to Use Them

Slimeballs are needed for sticky pistons, leads and slime blocks. The best way to farm them is to find a slime chunk. These are special chunks where slimes spawn deep underground, no matter the light level or biome.

This guide explains how slime chunks work in both editions, how swamp slimes are different, and how to build a basic farm. To see slime chunks in your world right away, open the slime chunk finder and enter your seed.

Open the slime chunk finder

What a slime chunk is

The world is split into chunks of 16 by 16 blocks, running the full height of the world. About 1 in 10 chunks is a slime chunk.

In a slime chunk, slimes can spawn when:

• The spawn spot is below Y 40.
• There is a solid block to spawn on and enough space for the slime.
• The difficulty is not Peaceful.

Light level does not matter for slime chunk spawning. That means you can light up the area to stop other mobs while slimes keep spawning.

Slime chunks look completely normal. There are no blocks or particles that show them. You need a map, a tool or patience to find one.

The pattern looks random, and in a way it is. Each chunk gets its own yes or no answer from a formula. Slime chunks can appear alone, in pairs, or in small clusters. There is no trick to predict them by looking at the land, so a map is the only fast way. Biome does not matter either, except mushroom fields, where no hostile mobs spawn at all.

Java vs Bedrock slime chunks

This is the biggest difference between the editions:

In Java, the slime chunk pattern comes from the world seed and the chunk position. Different seeds have different slime chunks.

In Bedrock, slime chunks only depend on the chunk position. Every Bedrock world has the same slime chunks at the same coordinates. A slime chunk at a spot in one Bedrock world is a slime chunk in every Bedrock world.

Set the right edition in the slime chunk finder, or you will see the wrong pattern.

Swamp slimes

Slimes also spawn on the surface in swamps and mangrove swamps, whether or not the chunk is a slime chunk. Swamp slimes follow different rules:

• They spawn between Y 51 and Y 69.
• The light level must be 7 or less, so they mostly spawn at night.
• They spawn more often around a full moon and never during a new moon.

Swamp slimes are fine for a few early slimeballs. For a real farm, a slime chunk is much more reliable, because it works all day at any light level.

How to find a slime chunk

1. Use a map. Enter your seed in the slime chunk finder. Green squares mark slime chunks. Click one to copy its coordinates or a /tp command.
2. Show chunk borders. In Java, press F3 and G to see chunk borders in game. This helps you mark the exact edges.
3. Check chunk math. A chunk covers block X from chunk X times 16 to that plus 15. The chunk calculator converts for you.
4. Find one by hand. Dig a big room below Y 40 and wait. If slimes keep spawning in a non-swamp area, you are in a slime chunk.

Building a simple slime farm

A basic farm only needs a cleared area and a way to kill the slimes.

• Dig out the chunk below Y 40. The more open floor space, the more spawns. Several layers stacked 3 blocks apart work well.
• Light everything up. This stops zombies, skeletons and creepers. Slimes ignore light in slime chunks.
• Stand at the right distance. Mobs do not spawn within 24 blocks of you, and they despawn beyond 128 blocks. Stand in between, often directly above the farm.
• Collect the slimes. Water streams can push slimes to a kill area. Iron golems attract slimes and kill them, or you can fight them yourself.

Big slimes split into medium ones, which split into small ones. Only the small slimes drop slimeballs, so you need to kill all three sizes.

Common mistakes

• Building above Y 40. Slime chunk spawning stops there.
• Using the wrong edition on a map. Java and Bedrock patterns are different.
• Building in a mushroom fields biome. No hostile mobs spawn there, slimes included.
• Leaving dark caves nearby. Other mobs fill up the mob cap and slow your farm down.
• Standing too close or too far. Stay between 24 and 128 blocks from the spawning floors.
• Forgetting the difficulty. On Peaceful, no slimes spawn at all, even in a perfect slime chunk.

Getting the most out of a slime farm

A slime chunk works best when slimes are the only mobs that can spawn nearby. Hostile mobs share a mob cap. If caves around you are full of zombies and skeletons, fewer slimes can spawn.

• Light up nearby caves. Or fill them in, if they are close to the farm.
• Pick a spot under an ocean. Oceans have fewer caves and fewer surface mobs, so the cap stays free for slimes. Keep the farm below Y 40.
• Make floors wide. Large slimes need a 3 by 3 space and some headroom to spawn. Three-block gaps between floors fit all sizes.
• Use the full chunk. Dig out all 16 by 16 blocks on each floor.
• Check neighbor chunks. Slime chunks often sit next to other slime chunks. Two or more side by side make a much stronger farm.

Slimes also drop more items with Looting. A Looting III sword gives extra slimeballs from each small slime.

What can you craft? Slimeballs make sticky pistons, leads, magma cream, slime blocks and the sticky part of honey and slime flying machines. A slime block is nine slimeballs, and it is great for bouncy floors and redstone builds.

If you play Bedrock, you can also look up a slime chunk once and reuse the spot in any world, since the pattern never changes between Bedrock worlds.

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