Chunky Minecraft: How to Pregenerate Your Map (Complete Guide)

Terrain generation is one of the most resource-intensive tasks for a Minecraft server. Every time a player explores an unknown area, the server must calculate the terrain, biomes, caves, structures, and ores in real-time, and since 1.18, the generation height has doubled, making the operation even more demanding.

The chunky mod solves this problem by pregenerating the Minecraft map before players explore it. No more freezes in every new area: the terrain is already ready, and the server only has to load it from the disk. It is one of the most recommended performance mods for any serious server.

This complete guide covers installation, commands, shapes, recommended sizes, and optimization techniques to efficiently pregenerate your Minecraft map with Chunky.

What is Chunky and Why Pregenerate?

When a player moves in an unexplored direction, Minecraft generates the chunks on the fly. Each chunk is 16×16 blocks across the entire height of the world (from -64 to 320 since 1.18). This generation engages the CPU for several hundred milliseconds per chunk, causing TPS drops and visible micro-freezes for all connected players.

The chunky mod pregenerates these chunks in advance, outside of play hours or before the server launch. Once the area is generated, the chunks are stored on the disk and loaded almost instantly. The result: stable TPS at 20, even when ten players explore in different directions.

Pregeneration is particularly useful in three situations: at the launch of a new server or a new season, after a Minecraft version change that modifies terrain generation, and on survival or adventure servers where exploration is at the heart of the gameplay.

Chunky Mod (Pregeneration) vs Chunky Render (3D Software)

Be careful not to confuse the two projects with the same name. The Chunky mod (also called Chunky plugin) is a Minecraft mod/plugin that pregenerates chunks server-side. This is the one we are discussing in this guide. It is installed in the /mods (Fabric/Forge) or /plugins (Paper/Spigot) folder and is used via in-game commands.

Chunky render, on the other hand, is an independent 3D rendering software that allows you to create photorealistic images of your Minecraft worlds. It is a graphic creation tool, not a server performance tool. If you are looking to generate renders of your constructions, it is an entirely different project.

In this guide, all commands and instructions concern exclusively the Chunky pregeneration mod.

Chunky Mod vs Chunk Pregenerator: Which Tool to Choose?

Two pregeneration tools coexist in the Minecraft ecosystem, and they are often confused. The Chunky mod works on Fabric, Forge, NeoForge, Paper, and Spigot. It stands out for its simplicity: a few commands are enough to start a circular or square pregeneration. It is lightweight, asynchronous, and automatically manages pause/resume.

Chunk Pregenerator is a mod exclusively for Forge/NeoForge (and Fabric via a port) that offers more advanced features: world border generation, named tasks, different syntax with /pregen. It is particularly suitable for heavy modded servers where Forge compatibility is essential.

In summary: Chunky is the recommended choice for Paper/Spigot and for most use cases due to its simplicity. Chunk Pregenerator is preferable on Forge/NeoForge servers with mod packs, as it integrates better into the modded ecosystem. Both do the same job: pregenerate terrain. The difference is in the platform and advanced options.

👉 Complete Guide Chunk Pregenerator (Forge/NeoForge)

Installing Chunky on Your Server

The installation of the chunky mod varies depending on your platform. For Paper or Spigot servers, download the .jar file from Modrinth and place it in the /plugins folder. For Fabric servers, the file goes in the /mods folder (Fabric API is required). For Forge and NeoForge, the same principle applies in the /mods folder.

On OuiPanel, the procedure is simple: access the File Manager, navigate to the /plugins or /mods folder depending on your server type, upload the Chunky .jar file, then restart the server. The mod is automatically detected at startup.

After restarting, check that Chunky is properly loaded by typing /chunky in the console or in-game. If the command returns the list of subcommands, the installation is successful. Also, ensure that your Java version is up to date (Java 17 minimum for Minecraft 1.18+, Java 21 recommended for 1.21+).

Basic Commands

Before starting pregeneration, you need to define three parameters: the target world, the center of the area, and the radius. Here is the complete sequence:

/chunky world <world_name> — Selects the world to pregenerate. By default, it's "world" (the Overworld). For the Nether, use "world_nether"; for the End, "world_the_end".

/chunky center <x> <z> — Sets the center of the pregeneration area. To center on the spawn, simply use /chunky spawn.

/chunky radius <blocks> — Sets the radius in blocks around the center. For example, /chunky radius 5000 will pregenerate an area with a diameter of 10,000 blocks.

/chunky start — Starts pregeneration with the defined parameters. Chunky then displays the progress percentage, the number of chunks generated, and the processing speed.

Here is a concrete example to pregenerate a circle of 5,000 blocks around the spawn:

/chunky world world
/chunky spawn
/chunky radius 5000
/chunky shape circle
/chunky start

Pregeneration runs in the background without blocking the server. Players can continue to play during the process, although performance is slightly reduced (which is why it is preferable to pregenerate before launch or during off-peak hours).

For servers with multiple worlds (Overworld, Nether, End), repeat the sequence for each world by changing the /chunky world parameter. Custom dimensions added by mods (Twilight Forest, Aether…) are also supported — use the internal name of the dimension as it appears in your server folder.

Advanced Commands and Patterns

Beyond the basic commands, Chunky offers advanced options to customize pregeneration according to your needs.

Available Shapes

The command /chunky shape <shape> allows you to choose the geometry of the area to pregenerate. The available shapes are as follows.

circle — The default and most recommended shape. It pregenerates a circle around the center, which corresponds to the natural way players explore (in all directions). A circle with a radius of 5,000 blocks covers about 78.5 million blocks² and consumes less disk space than an equivalent square.

square — Pregenerates a square. Useful if your chunk map corresponds to a square world border. A square with a radius of 5,000 covers 100 million blocks² (about 27% more than a circle of the same radius).

diamond — Pregenerates a diamond (square rotated 45°). Rarely used, but may correspond to certain world configurations.

rectangle and ellipse — For non-symmetrical areas. The syntax requires two radii: /chunky radius <x> <z>. For example, /chunky radius 5000 3000 for a rectangle or ellipse of 10,000×6,000 blocks.

pentagon, triangle, star — Exotic shapes rarely useful in practice, but available if your worldborder has a particular shape.

For most servers, circle is the best choice: it covers the useful area without wasting disk space in the corners.

Management Commands

/chunky pause — Pauses pregeneration and saves progress. Essential if you need to temporarily free up resources (for example, a peak of connected players).

/chunky continue — Resumes pregeneration exactly where it left off. No data is lost.

/chunky cancel — Completely cancels the current task. The already generated chunks remain on the disk, but the progress is reset.

/chunky progress — Displays progress: percentage, number of chunks processed, speed (chunks/second), and estimated time remaining.

/chunky silent — Disables progress messages in the console. Useful if the logs become too verbose during a long pregeneration.

/chunky pattern <pattern> — Changes the order of chunk generation. The default pattern "concentric" (from the center outward) is the most recommended, as it prioritizes the most frequented areas.

Map Size: How Much to Pregenerate?

The choice of pregeneration radius depends on your server type, the number of players, and your available disk space. The larger the radius, the more time and space pregeneration takes.

Radius of 1,000 blocks — Area of 2,000×2,000 blocks. About 1 GB of disk space. Estimated time: 5-15 minutes. Suitable for small creative servers or mini-game server spawns. Minimum RAM: 4 GB.

Radius of 3,000 blocks — Area of 6,000×6,000 blocks, or about 9 million blocks² in a square. About 3-5 GB of disk space. Estimated time: 30-60 minutes. It's the right compromise for a survival server of 5-10 players. Minimum RAM: 4-6 GB.

Radius of 5,000 blocks — Area of 10,000×10,000 blocks. About 8-12 GB of disk space. Estimated time: 1-3 hours. Recommended for active survival servers with 10-20 players. Minimum RAM: 6-8 GB.

Radius of 10,000 blocks — Area of 20,000×20,000 blocks. About 17-25 GB of disk space. Estimated time: 4-12 hours. For large community servers with 20+ regular players. Minimum RAM: 8 GB.

Radius of 15,000 blocks — Area of 30,000×30,000 blocks. About 35-50 GB of disk space. Estimated time: 12-36 hours. Reserved for large-scale servers. Minimum RAM: 10 GB.

Radius of 20,000 blocks — Area of 40,000×40,000 blocks. More than 60 GB of disk space. Estimated time: 24-72 hours. Excessive for most servers, but relevant for very active communities that explore massively.

These estimates vary depending on CPU power, Minecraft version, and installed mods. A modded server generates more slowly than a vanilla or Paper server, as each mod can add content to the chunks (structures, ores, custom biomes).

Our recommendation: start with a radius of 3,000-5,000 blocks, then expand if necessary. It is always possible to relaunch a pregeneration with a larger radius — Chunky does not regenerate already existing chunks.

Don't forget the Nether: if your Overworld worldborder is 5,000 blocks, pregenerate the Nether with a radius of 625 blocks (the ratio is 1:8). For the End, a radius of 1,000-2,000 blocks around the spawn is usually sufficient.

Optimizing Pregeneration

Pregeneration is a heavy operation that can slow down your server if not managed correctly. Here is how to maximize efficiency.

OuiPanel Settings to Maximize Performance

Before launching significant pregeneration, adjust your server to allocate maximum resources.

Allocate enough RAM. Pregeneration is memory-intensive, especially on versions 1.18+ with extended world generation. If your plan allows, temporarily increase the allocated RAM by 2 GB during pregeneration. On OuiPanel, modify this setting in the Server Settings.

Pregenerate on an empty server. Ideally, launch pregeneration when no players are connected. Chunky is designed to run in the background, but it will be significantly faster without the load of players, mobs, and active plugins.

Check your disk space. Before launching a 10,000-block radius, ensure you have at least 25-30 GB free. On OuiPanel, disk space is visible in the Dashboard. If you are limited, pregenerate a smaller radius or switch to a plan with more storage.

Set a worldborder. Configure a world border that matches your pregeneration radius. Vanilla command: /worldborder set <diameter>. This prevents players from exploring beyond the pregenerated area, which would make pregeneration pointless.

Pregenerate in Multiple Steps

For large areas (radius over 10,000 blocks), pregeneration can take dozens of hours. Instead of launching everything at once, proceed in steps.

Step 1: The spawn (radius 1,000). First, pregenerate the immediate spawn area. This is the most frequented area and where freezes are most visible. Time: 5-15 minutes.

Step 2: The main play area (radius 5,000). Relaunch with a larger radius. Chunky automatically detects already generated chunks and does not recalculate them. Only new chunks are processed. Time: 1-2 additional hours.

Step 3: The extended area (radius 10,000+). If your community actively explores, gradually expand. You can launch this step overnight with /chunky start, and it will complete itself.

This step-by-step approach has a concrete advantage: it prioritizes the most important areas. If you need to open the server quickly, players already have a smooth spawn area while the rest generates in the background.

Advanced Tip: If your server restarts automatically (OuiPanel scheduling), Chunky can automatically resume on restart if you add auto-continue: true in the config.yml configuration file. This ensures that pregeneration does not stop permanently after a scheduled restart.

In case of problems: If pregeneration seems stuck or abnormally slow, check three things. First, that the allocated RAM is not saturated (a server in swap pregenerates 10 times slower). Then, that disk space is sufficient (Chunky stops silently if the disk is full). Finally, that other heavy plugins do not monopolize the CPU in parallel — custom structure generation plugins like Terra or Iris (the terrain generator, not the shader) can conflict with pregeneration.

Which Hosting for Efficient Pregeneration?

The speed of pregeneration directly depends on your server's power. Three factors count: the CPU (high single-core frequency), RAM (4 GB minimum, 6-8 GB for large radii), and NVMe SSD storage (chunks are continuously written to the disk during pregeneration).

On a OuiHeberg server, processors run at high frequency, and storage is exclusively NVMe, allowing optimal pregeneration speeds. For a 5,000-block radius on Paper 1.21, expect about 1-2 hours on a 6 GB plan.

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Pregeneration with the chunky mod is one of the most impactful optimizations for a Minecraft server. With a few commands and a few hours of patience, you permanently eliminate freezes related to terrain generation and offer a smooth experience to your players from day one.

Start with a reasonable radius (3,000-5,000 blocks), set a corresponding worldborder, and expand over time. And if your server is on Forge with a mod pack, consider checking if Chunk Pregenerator might be more suitable for your configuration.