Why your mob farm is slow: spawn caps, not spawn rates
Mobs stop spawning because the cap is full of something else, somewhere else. Here is how the per-category cap works, what counts toward it, and how to empty it.
A mob farm that "stopped working" almost never has a broken spawner platform. It has a full spawn cap being eaten by mobs somewhere you are not looking.
The cap is global and per-category
Minecraft counts mobs per category, across all loaded chunks, not per farm:
| Category | Cap, roughly, per player |
|---|---|
| Monster | 70 |
| Creature (animals) | 10 |
| Ambient (bats) | 15 |
| Water creature | 5 |
| Water ambient | 20 |
| Axolotl | 5 |
When the monster count reaches the cap, nothing else hostile spawns anywhere in your loaded area — including your farm. The two hundred zombies wandering an unlit cave a few hundred blocks away are why the farm is dry.
The fix is removing competition, not enlarging the farm
Three approaches, in order of effort:
- Light or slab the caves inside your simulation distance. Tedious, permanent.
- Move the farm somewhere nothing else loads — an ocean, or the Nether roof.
- Remove the spawnable surface rather than lighting it. More reliable, because the
modern threshold is light 0 and one missed corner keeps producing.
Mobs must be more than 24 blocks away
Hostile mobs spawn between 24 and 128 blocks from the player. Standing on your own platform stops it spawning. The AFK spot needs to be at least 24 blocks off, usually above or below.
The 128-block outer edge is a sphere, and past it mobs despawn instantly. That is why a farm produces while you stand still and stops the moment you wander.
Two despawn rules people conflate
- Instant — beyond 128 blocks, no randomness involved.
- Random — between 32 and 128 blocks, a chance per tick. Inside 32 blocks, never.
A mob with a name tag, a picked-up item, or PersistenceRequired never despawns at all. That is how a farm platform slowly silts up with armoured zombies that block new spawns.
Simulation distance is the real radius
Mobs tick only in chunks inside simulation-distance, not view-distance. Lowering it for TPS also shrinks the area your farm draws from — and shrinks where the competition comes from. It cuts both ways, so change it knowing which you care about.
Light 0, not light 7
Java has spawned hostiles only at block light 0 since 1.18. Anything saying "light level 7" predates that. Bedrock still uses 7. Getting it backwards means either over-lighting a build or leaving a farm bright enough to do nothing.
Look up drop tables, XP values and the real loot-table ids for any mob in the Mob Drops & Loot Table Browser.