How to use the Slime Chunk Finder
Slimes spawn below Y=40 in specific 'slime chunks' that depend on the world seed (Java) or the chunk position alone (Bedrock). Turn on the grid and zoom in: the green hatched chunks are where slimes can spawn regardless of light level.
- Enter your seed and choose Java or Bedrock. The two editions use completely different slime chunk formulas.
- Zoom in until chunk outlines appear. Slime chunks are hatched in green.
- Hover a chunk to read its chunk coordinates and block range, then dig out a room below Y=40 (Y=30 or lower is ideal).
- Look for two or more adjacent slime chunks for a larger, more productive farm.
How slime chunks are chosen
On Java Edition, each chunk's X and Z are mixed with the world seed and fed to Java's random number generator. The chunk is a slime chunk when the first number it rolls out of 10 is zero, so about 1 in 10 chunks qualifies, and the pattern changes completely with the seed.
Bedrock Edition ignores the seed. It seeds a Mersenne Twister with the chunk coordinates alone, so every Bedrock world has exactly the same slime chunks. A Bedrock slime chunk list from one world works in all of them.
Building a slime farm
Slimes spawn in slime chunks below Y=40 at any light level, as long as there is a solid block with two blocks of air above it. Clear a large flat area across one or more slime chunks, ideally lower than Y=30, and stack several spawning floors with at least three blocks of headroom each (big slimes are just over two blocks tall).
Light up, or fill in, every cave within 128 blocks so that other mobs don't use up the mob cap. Then wait 24 or more blocks away and let slimes walk into a kill chamber or onto magma blocks. Slimes do not spawn on Peaceful, and they also spawn in swamps and mangrove swamps on the surface depending on the moon phase.
Starting a new world for a slime farm? The slime seed finder (Java) searches millions of seeds a second for the most slime chunks around your farm spot, or for an exact pattern such as a 2×2 square of slime chunks.
Editions and versions
| Dimension | Overworld |
|---|---|
| Editions | Java & Bedrock, up to 26.3 |
Questions
Why do slime chunks differ between Java and Bedrock?
Java derives slime chunks from the world seed and chunk coordinates with the Java Random generator. Bedrock uses a Mersenne Twister seeded only by the chunk position, so slime chunks are the same in every Bedrock world.
At what Y level do slimes spawn in slime chunks?
Below Y=40 in a slime chunk, at any light level. Slimes also spawn in swamp biomes on the surface between Y=51 and Y=69, depending on the moon phase, independent of slime chunks.
How do I know which chunk I am standing in?
Press F3 in Java and read the 'Chunk' line, or divide your X and Z coordinates by 16 and round down. The map's coordinate readout also shows the chunk under the cursor.
How many chunks are slime chunks?
About 10% on both editions. Clusters of two to four touching slime chunks are common enough that you can usually find one within a few hundred blocks of spawn.
Does light level matter for slimes in slime chunks?
No. Inside a slime chunk below Y=40, slimes ignore light level, so you can light up the farm for safety without affecting slime spawns.
Updated · data for Minecraft Java & Bedrock up to 26.3