How to Pre-Generate a Minecraft World with Chunky

Generating new terrain is the heaviest work a Minecraft server does, and it's what causes lag when players explore. Chunky generates it all ahead of time, while nobody is playing. Pair it with a world border so players can't walk past the generated area.

Install Chunky

Download Chunky for your platform from Modrinth and upload it in Files: into plugins on Paper and Purpur, or into mods on Fabric, Forge and NeoForge, along with any dependency the page lists. Restart the server. Players don't need it.

Pick a radius

Generation time and disk use grow with the square of the radius:

2000–3000 is plenty for friends. 5000 is typical for a public server. A 10000 radius can take several gigabytes, so check your storage first.

Set the border and start

In the Console:

worldborder center 0 0
worldborder set 10000
chunky worldborder
chunky start

worldborder set takes the full width, so 10000 means 5000 in each direction. chunky worldborder copies that border into Chunky. Players at the border still load chunks outside it, up to their view distance. To cover those too, set the radius yourself with chunky radius, adding view-distance × 16 to it.

Progress, speed and time remaining print to the console. chunky pause and chunky continue stop and resume it, even across restarts. Run it before opening the server or overnight: it keeps the CPU busy, and players online will feel it.

For the Nether, one block covers eight in the Overworld, so an eighth of the radius is enough:

chunky world world_nether
chunky radius 700
chunky start

On Fabric and Forge, worlds are named minecraft:the_nether and so on.

When it finishes, take a backup in Backups so you never have to run it again.