Minecraft Slime Chunk Finder

A chunk where slimes are allowed to spawn underground. Roughly one chunk in ten is one, and which ones are decided by hashing the world seed together with the chunk coordinates when the world is created. Nothing you do in game changes it, and it never moves. In every other chunk, slimes simply will not spawn below ground no matter what you build.

Almost always height, mob cap or distance. Slimes only spawn below Y 40, so a platform at Y 60 will never produce one. They also compete with every other hostile mob for the same cap, so if the caves around your farm are open and dark they will fill it first, and lighting or walling those off is what usually fixes a dead farm. Finally you have to be between 24 and 128 blocks away for anything to spawn at all, so standing inside the farm stops it working. Peaceful difficulty removes slimes entirely.

Not in any version you would run a server on. The odds and the height limit both moved around in Alpha and early Beta, settling at one in ten chunks in Alpha v1.1.1 and at Y 40 in Beta 1.9. Nothing has changed since, so a slime chunk in 1.8 is still a slime chunk in 26.2 for the same seed. That is why this tool has no version selector when most seed tools need one.

No, and it is worth knowing why. Bedrock works out slime chunks without using the world seed at all, so they sit at the same coordinates in every Bedrock world ever made. A Bedrock slime chunk map is a single fixed pattern rather than something you look up per seed, so entering your seed here would be meaningless. This tool is for Java Edition.

Run /seed in the game if you have permission to use commands. On a server, an operator can run it from the console. In single player you can also find it on the world options screen. Paste it in exactly as it appears, including a minus sign if it has one.

Not at all. When the seed box does not contain a number, Minecraft turns the text into one by hashing it, and this tool does exactly the same thing, so the answer is still correct. It will tell you when it has done so. The same happens if you paste a number too large to be a seed, which catches people out, because the world you get is nothing like the number you typed.

No. Swamps are the second way slimes spawn and they ignore slime chunks entirely. In a swamp they spawn at the surface between Y 51 and Y 69, in the dark, and much more often on a full moon than a new one. That makes a swamp farm simpler to build and far less consistent, since it stops working every time the moon or the weather turns against you.