Loaded chunks and why they matter

Chunks are the basic unit of world storage in Minecraft: 16 by 16 blocks horizontally, spanning the full build height. Loaded chunks are the ones currently active in memory, ticking entities and processing block updates. The more chunks your server has loaded, the more RAM it uses and the more work it does every tick.

What a loaded chunk is

A chunk is loaded when a player is within range of it, or when something keeps it loaded by other means: a chunk loader plugin, a nether portal, a spawn area, or certain command blocks. Loaded chunks stay in memory and tick at full rate, meaning mobs move, crops grow, and redstone fires. Unloaded chunks are dormant.

View vs simulation distance

Paper distinguishes between two settings that are often confused:

• View distance: how many chunks around each player the server sends to the client. This is what the player sees.
• Simulation distance: how many chunks around each player actually tick. Only entities and blocks in the simulation radius actively update.

You can set view distance to 12 and simulation distance to 6, giving players a wide view while keeping the actually-ticking area smaller. On servers with 30 or more players, reducing simulation distance from 10 to 6 can meaningfully cut entity ticking overhead.

Chunk count and memory

Each loaded chunk takes roughly 4 to 8 KB of heap memory on its own, before accounting for entities and tile entities inside it. A server with 10 players spread across multiple worlds at view distance 12 can easily have 3,000 to 5,000 chunks loaded simultaneously. That's manageable on its own, but high chunk counts also mean more entities to tick and more block updates to process.

Worlds with large spawn areas or automatic chunk-loading mechanisms can hold thousands of chunks permanently. These are worth checking if memory climbs faster than expected.

What clan.me tracks

The plugin records per-world loaded chunk counts with each heartbeat. You can see which world is holding the most chunks at any given time and track whether that number is growing over server uptime, which can indicate a chunk leak or a spawn area expanding beyond its intended size.