A Minecraft mob farm usually fails because the world is on Peaceful, the room is not fully dark, the AFK spot is wrong, or drops are missing the collection system. The reliable vanilla build is simple: a block-light-0 room, water transport, a kill chamber, and hoppers feeding chests. Use the sections in this order to build it, test it, and fix the common failure points.
Build the basic dark room farm
Start with the standard Survival dark-room design, because it works in current Java Edition and Bedrock Edition when the spawn rules are right.
- 1.Use a Survival world on Easy, Normal, or Hard; hostile mob farms do not work on Peaceful.
- 2.Place the farm where few other hostile-spawn spaces are loaded, commonly high above ground or over ocean.
- 3.Build enclosed full-block spawning platforms, then add a roof so skylight cannot reach the floor and the block light level is 0.
- 4.Add Trapdoors, Buttons, or water channels so mobs walk or get pushed into streams.
- 5.Route the water to a drop shaft or kill chamber.
- 6.Put Hoppers under the kill area and feed them into Chests.
Set difficulty and commands before testing
Hostile farms need Easy, Normal, or Hard. If commands are enabled, open Chat and run /difficulty easy, /difficulty normal, or /difficulty hard; Bedrock also accepts 1 for Easy, 2 for Normal, 3 for Hard, and 0 for Peaceful.
To enable commands in Bedrock singleplayer, open Settings > Game and turn on Allow Cheats. In Java, turn on Allow Commands while creating a new world, or use World Options and Allow Commands for an existing singleplayer world.
For a Java LAN test, open the game menu, choose Open to LAN, then use Settings for Other Players to set Game Mode and Allow Commands. In Bedrock, turning on Allow Cheats permanently disables achievements for that world.
Pick an AFK spot that activates spawns
Your player position decides whether the dark room can produce mobs. Stand so the spawning floor is more than 24 blocks from you and still inside the outer spawn range your edition is actually using. In Java Edition that outer limit is 128 blocks. In Bedrock Edition it follows Simulation Distance, which defaults to 4 chunks, and at that setting mobs only spawn between 24 and 44 blocks and despawn once they are past 44 blocks. On Bedrock, raise Simulation Distance to 6 or higher before you count on a longer AFK spot.
High above ground or over ocean is common because fewer other valid hostile-spawn spaces stay loaded nearby. Exact mob caps and spawning ranges differ by edition and simulation distance, so treat the AFK spot as part of the build.
If this method fails, move your AFK spot before rebuilding the farm: keep the floor outside 24 blocks, keep it within the outer limit for your edition and Simulation Distance (128 blocks in Java, but only about 44 blocks in Bedrock at the default Simulation Distance of 4), and reduce other loaded spawn spaces around it.
When mobs are not spawning
Light and world settings are the most common reason a dark-room farm stays empty.
Seal the room and roof it so skylight does not reach the spawning platforms. Current hostile-spawn spaces need block light level 0, so skip older light-level-7 advice.
Confirm the world is not on Peaceful. For command-enabled worlds, open Chat and run /gamerule doMobSpawning true so natural mobs can spawn into the game.
When the room is dark and the rules are correct, check placement again. A farm surrounded by loaded ground or other valid spawn spaces competes with the spawning floor.
Make drops land in chests
Collection starts with Hoppers directly under the kill area feeding into Chests. For campfire chambers, place the Hopper directly under the Campfire so drops fall into storage.
Drops can be disabled in command-enabled worlds. Open Chat and run /gamerule doMobLoot true; Bedrock documents domobloot as the rule that controls whether mobs drop loot.
Natural spawning has its own rule. If the spawning room is built correctly but nothing appears, open Chat and run /gamerule doMobSpawning true; Bedrock documents domobspawning as the rule controlling whether mobs spawn into the game.
When the kill chamber wastes drops
The most common kill-chamber cause is a design that leaves mobs alive or destroys items before hoppers collect them.
For a fall grinder, push mobs with water into a vertical drop. Use at least 24 blocks for automatic kills on most common hostile mobs, use more height for witches or armored mobs, and shorten the drop when you want XP from manual hits.
For campfire damage, route mobs into a one-block kill space with a Campfire or Soul Campfire, then stop the water before it interferes with the fire. Soul Campfires kill faster when available, but witches are a poor target because they can heal and use Fire Resistance.
For lava and magma designs, protect the item path. Lava blades can destroy drops when built incorrectly, baby zombies need a safety barrier in some layouts, and Magma Blocks are not effective against fire-immune Nether mobs such as blazes and wither skeletons.
Spawner farms from dungeons and structures
This fixes the need to rely on natural hostile spawning once you find a natural Monster Spawner.
Find a natural Monster Spawner in a dungeon, mineshaft, fortress, bastion, stronghold, or mansion.
Leave the Monster Spawner intact, because vanilla Survival does not let you move it.
Stand within 16 blocks of the Monster Spawner so it activates.
Clear spawning space around it. Java-style designs generally use the surrounding 9 x 3 x 9 volume, and Bedrock designs need to account for the diamond-shaped horizontal range.
Keep the light conditions required by that spawner's mob type.
Move spawned mobs away from the Monster Spawner with water, signs, blocks, a drop, an elevator, or a kill chamber so it can continue spawning.
Finish with a fall, campfire, lava, magma, or manual kill chamber and Hopper-to-Chest collection.
Older tutorial advice to skip
Older guides may still recommend light level 7 or lower for dark rooms, or claim that Silk Touch can move a Monster Spawner in vanilla Survival. Use the current rules instead: hostile spawning needs block light level 0 with a roof, and movable or configurable spawners belong to Creative, commands, pick block, or spawn egg setups.
In Survival, keep the choice simple. Build a natural dark-room farm, or build around an intact natural Monster Spawner you found.
Bedrock XP farms with a trident killer
Use this only for Bedrock farms, because Java trident mechanics do not support the common Bedrock-style trident-killer design the same way.
- 1.Build a small chamber where Pistons repeatedly move a thrown Trident.
- 2.Throw the Trident into the chamber yourself.
- 3.Route mobs into that chamber from the farm.
- 4.Keep the Piston mechanism running so moved Trident hits count as player hits.
- 5.Stand nearby with the farm loaded and collect XP and drops with Hoppers and Chests.
Frequently Asked Questions
Can a mob farm work on Peaceful?
No. Hostile mob farms need Easy, Normal, or Hard. In a command-enabled world, run /difficulty easy, /difficulty normal, or /difficulty hard; commands require cheats or permissions.
How far away should I stand from a mob farm?
Stand more than 24 blocks from the spawning floor, and stay inside the outer spawn range your edition is using. Java Edition uses 128 blocks. Bedrock Edition follows Simulation Distance, which defaults to 4 chunks, and at that setting mobs only spawn out to about 44 blocks and despawn past 44 blocks, so raise Simulation Distance to 6 or higher if you want a farther AFK spot. Exact mob caps also differ by edition.
Can I use Silk Touch to move a Monster Spawner?
No. Current vanilla Java Edition and Bedrock Edition Survival do not let you obtain a Monster Spawner with Silk Touch. Spawners can be obtained or configured through Creative inventory, commands, pick block, or spawn eggs in Creative or cheats contexts.
How do I make the farm give XP instead of only drops?
Shorten a fall-damage grinder so mobs survive with low health, then hit them from a protected opening. On Bedrock, a trident killer can count moved trident hits as player hits when you throw the trident yourself.
