The seed determines what your world looks like: which biomes, villages, structures and landscapes get generated. A good seed can give your SMP a spawn location with everything within reach; a bad one drops you in the middle of an ocean.
What is a seed
A seed is a number that Minecraft uses as a starting point for world generation. The same seed on the same version always generates the same world. An empty seed field produces a random number.
Setting the seed
In server.properties:
level-seed=123456789
You can enter a number or a word. Minecraft converts words into a number. Set the seed before the first startup. After generation, changing the seed has no effect on existing terrain; only new chunks use the new seed, which creates a visible seam in your world.
Preview the map
Use ChunkBase Seed Map. Enter the seed and your Minecraft version and you see the complete map: biomes, villages, temples, strongholds and more. This way you know before starting whether the seed is suitable.
What to look for in an SMP seed
- Spawn biome: a flat grass biome with trees is ideal for a spawn town. Spawning on a mountain or in a jungle makes building difficult.
- Nearby structures: a village within 500 blocks of spawn gives players immediate access to a blacksmith and beds.
- Biome variety: a seed with many different biomes near spawn gives players more to explore.
- Nether portal location: check if the Nether fortress is reachable without travelling thousands of blocks.
Seeds for 26.3
Minecraft 26.3 includes new structures and biome adjustments. Seeds from earlier versions generate different worlds on 26.3. Search specifically for 26.3 seeds on forums like r/minecraftseeds or use ChunkBase with the 26.3 option selected.
Setting the seed is one of the first steps when starting a Minecraft server.
Can I change the seed later?
Not without generating a new world. The seed is tied to existing chunks. If you want a new seed, back up the current world, delete the world folder, and the server generates a new world with the new seed on the next start.
Do the Nether and the End use the same seed?
Yes. All dimensions use the same seed, but the generation algorithms differ per dimension. You cannot set them separately.
Can I find the seed of an existing world?
Yes. Type /seed in the console or in-game as an operator. The seed is displayed.
