🟩 Slime chunk finder
Slime chunks are the ~10% of chunks that spawn slimes below Y=40 regardless of biome. Which chunks they are depends only on the world seed, so they can be computed exactly. Toggle the 🟩 filter in the map below.
How it works
Every chunk runs a deterministic pseudo-random check seeded by the world seed and the chunk's coordinates. If the check passes, that chunk is a slime chunk forever. No biome, structure or terrain affects it — which is why this is one of the few things a seed tool can state exactly.
FAQ
Do slime chunks change between versions?
No. The slime-chunk algorithm has been stable for years, so a slime chunk is the same in Java 1.16 through 1.21.
Do slimes also spawn in swamps?
Yes — swamp biomes spawn slimes at night between Y=50 and Y=70. Slime chunks are the underground method.
Does this work on Bedrock?
This page computes Java slime chunks. Bedrock uses a different worldgen, so treat results as approximate there.