How to pregenerate your Minecraft world so exploring does not lag

Every time a player walks into land nobody has visited, the server has to generate it, and generating new land is some of the heaviest work a Minecraft server does. Pregenerating does that work in advance, in one go, so players exploring around spawn never wait for chunks to load. The panel runs it for you with Chunky, a free pregeneration tool, so you do not need to install anything or type commands.

Start a pregeneration

1. Open your server in the panel and click Modding in the server's tabs.
2. Open the Worlds tab, then click Your worlds. It lists your worlds. One of them is marked Active, the world your server loads.
3. Open the actions menu of the active world and choose Pregenerate the land. Pregeneration works on the active world only. If you want another world, first choose Make this the active world in the same menu.

4. In the dialog Pregenerate (with the world's name), choose:

   • How far from the centre: a distance in blocks, from the choices shown, or Another distance to type your own. The dialog says Your plan allows up to a maximum, and bigger plans allow larger distances. A distance of 5,000 blocks covers a square 10,000 blocks across.
   • Centre: the World spawn, or the middle of the map at (0, 0).
   • Also generate: The Nether (out to an eighth of the distance, so it matches where portals lead) and The End (around the main island; most of the End is empty space, so this is rarely needed).
   • Pause while players are online: generating uses most of the server, so this pauses it within a minute of someone joining and carries on when the server is empty.
5. Read the estimate line, for example how many chunks, how much more disk and about how long. Click Start pregenerating.

If Chunky is not on your server yet, the panel adds it first and restarts the server once to load it. If it is already there, the dialog says so. You can follow progress on the page or leave. A bell notification tells you when it is done.

Follow, pause or stop it

While it runs, a progress card appears above the list of worlds, called Pregenerating and the world's name. It shows the percentage for each dimension, how many chunks per second and how much time is left. You can Pause and Resume it, or Stop it. Stopping keeps the chunks already generated, and you can start again later.

Keep an eye on size and backups

Pregenerated land takes disk space, and a big distance makes a big world. The dialog warns you when the world would grow larger than your backup space, because backups of the server may then stop fitting. Choose a smaller distance, or add backup space. See How to create, download and restore backups.

When not to pregenerate

• If your world already has lots of explored land, pregenerating fills in the gaps and can make it much bigger.
• Pregeneration is not a fix for a server that is slow for other reasons. See How to reduce lag on your Minecraft server.
• To shrink a world that has grown, see How to trim unused chunks from your Minecraft world.

Good to know

• Something else may be running on your worlds, such as a download, a trim or a copy. The dialog then says Something is already running on this server's worlds and asks you to wait.
• If you set a world border, pick a distance that matches it.
• Pregeneration and trim need Paper, Purpur, Folia, Spigot, Fabric, Quilt, Forge or NeoForge, because they run Chunky as a plugin or a mod. On Vanilla, Sponge or a proxy, change the server type first, see How to change your Minecraft version or server type.

Planning a big survival world? See Minecraft server hosting.