How to Find Slime Chunks in Minecraft

Guide Java Bedrock

Quick answer: Slimes spawn below Y=40 in special 'slime chunks' - about 1 in 10 chunks, regardless of light. Java: your chunks depend on the world seed (press F3+G to see chunk borders). Bedrock: slime chunks are the same fixed coordinates in every world. Slimes also spawn in swamps at night (Y=51-69).

What you need

Java: F3 debug screen (F3 + G for chunk borders)
Your world seed (/seed) for chunk-finder tools
A pickaxe to dig down to Y=40 or below

Step by step

Underground method (both editions): slimes spawn below Y=40 in slime chunks, about 1 in 10 chunks, in any light level. Dig out a large room under Y=40 and see where slimes appear.
Java: press F3 + G to draw chunk borders in the world. A chunk runs 16x16 blocks; the debug screen also shows your current chunk.
Java: your slime chunks depend on the world seed. Run /seed, then plug the seed into a free chunk-finder map tool to mark every slime chunk around your base.
Bedrock: slime chunks sit at the same fixed coordinates in every world - any Bedrock slime-chunk map works without knowing your seed.
Swamp method: slimes spawn on the surface in swamps and mangrove swamps between Y=51 and Y=69 when the light level is 7 or less. They are most common on a full moon and never spawn on a new moon.
Farming tip: light up nearby caves to free the mob cap, then stand 24-32 blocks from your slime-chunk platform so slimes keep spawning.

Java vs Bedrock

Java slime chunks are seed-based; Bedrock slime chunks are fixed coordinates shared by every world. Swamp spawning is identical on both.

Versions: Slime chunk mechanics are stable across current versions. Swamp spawning (Y=51-69, light 7 or less, moon phases) works the same on Java and Bedrock.

Frequently asked questions

Do slimes need darkness in slime chunks?

No - below Y=40 they spawn at any light level. Only the swamp surface spawns care about light (7 or less).

Why is my slime farm empty?

Usually the mob cap is full of cave mobs, or you are standing too close (slimes do not spawn within 24 blocks of you). Light up caves around the farm.