Generating new terrain is the most expensive thing a Minecraft server does. When several players fly off in different directions with elytra, the server can fall behind and everyone lags. Pre-generating does that work once, in advance, while nobody's online.
1. Install Chunky
Install Chunky from the Plugins tab (Paper, Purpur) or the Mods tab (Fabric, Forge, NeoForge), then restart.
2. Pick a size
Each block of radius costs disk space and time. Rough guide:
| Radius | Area | Typical size on disk |
|---|---|---|
| 2,000 blocks | 4,000 × 4,000 | about 1 GB |
| 5,000 blocks | 10,000 × 10,000 | about 6 GB |
| 10,000 blocks | 20,000 × 20,000 | about 25 GB |
Actual size varies with terrain and mods. Check your plan's storage has room.
For a small group, 3,000 to 5,000 blocks is plenty.
3. Set a world border to match
Pre-generating only helps if players stay inside the area. Set a border the same size:
worldborder center 0 0
worldborder set 10000
worldborder set takes the full width, so a 5,000 radius is 10000.
4. Run Chunky
In the Console tab:
chunky center 0 0
chunky radius 5000
chunky start
It shows progress as it goes. You can stop it with chunky pause and carry on later with chunky continue. It picks up where it left off, even after a restart.
5. Do the Nether too
The Nether is an eighth of the size for the same Overworld distance, so a quarter of the radius covers it well:
chunky world world_nether
chunky radius 1250
chunky start
(On vanilla, Fabric and Forge the Nether is minecraft:the_nether.)
While it runs
Pre-generating uses a lot of CPU. Run it when nobody's playing, ideally overnight. Players can stay online but may notice some lag until it finishes.
Questions
How long does it take?
It depends on the radius, mods and your plan's CPU. A 5,000-block radius on a vanilla or Paper world often takes one to a few hours; heavily modded worlds take longer.
Does pre-generation help after a Minecraft update?
New structures and biomes only appear in chunks generated after the update, so pre-generated chunks keep the old terrain. Reset the area or extend the border after big updates if you want the new features.
Will this fill my disk?
It can. Check the table above against your storage and start smaller if you're unsure.