Farms / Combat / 1.21
How to Make a Mob Grinder in Minecraft
A mob grinder is a dark platform that spawns hostiles, water that flushes them into a single hole, and a drop tall enough to kill on impact. Get the height right (23 blocks) and the hoppers do the rest, while creepers, skeletons and zombies fall to their death without ever touching you.
The kill-tower loop
- 1Build a dark spawn platform up highMake a flat platform at least 24 blocks above the ground (or float it in the sky), walled in and fully lightproofed. Hostile mobs only spawn on solid blocks at light level 0, so a sealed dark room is the whole engine. A 9x9 or larger floor gives a good spawn rate.
- 2Flush mobs with water channelsRun water from each outer edge toward a single 1x1 hole in the centre. Water flows seven blocks, so size each channel to push every spawned mob into the drop hole. They get swept off the platform and into the shaft below.
- 3Drop them exactly 23 blocksFall damage is half a heart per block past the third, so a 23-block drop deals about 10 hearts and kills any 20-HP mob (zombies, skeletons, creepers). For a manual XP farm leave them at 22 blocks so they land at half a heart and you finish them with one punch.
- 4Catch the loot on a hopper floorAt the bottom of the shaft, lay a line of hoppers feeding a double chest. Drops and XP land in a 1x1 kill spot, the hoppers funnel every item to storage, and you stand at the wall to collect the experience orbs.
- 5Light the surroundings, not the platformTorch the area around the farm so mobs only spawn inside your dark room and not in nearby caves stealing the spawn cap. Keep the spawn platform pitch black; light everything else within 128 blocks so the cap is spent on your grinder.
What you need
Cobblestone (lots)
Water buckets
Hoppers
Double chest
Quick answers
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How high does the drop need to be?
Fall damage is 0.5 hearts per block above 3. A 23-block drop deals roughly 10 hearts and kills any normal 20-HP mob outright. Use 22 blocks if you want them alive at half a heart for a one-hit XP farm.
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Why are no mobs spawning?
Light level. The spawn platform must be at light level 0 on solid blocks, and you have to be within 24 to 128 blocks of it (the spawn range) but not too close. Light up nearby caves so the mob cap is not eaten elsewhere.
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How far does water flush mobs?
Source water flows 7 blocks before it stops. Lay your channels so no spot on the platform is more than 7 blocks from flowing water, and angle them all toward the single central drop hole.
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Do I get XP from a mob grinder?
Yes, if you finish the mobs yourself. A pure fall-damage farm gives item drops but little XP, because mobs killed by the environment drop no experience. Drop them to half a heart (22 blocks) and land the killing blow for full XP.
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Why is my farm slow?
Usually the spawn area is too small or too lit, or other dark spaces nearby are stealing the hostile mob cap (about 70 mobs per player). Expand the dark platform, seal every light leak, and torch surrounding caves to funnel the cap into your farm.
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Can creepers blow up the farm?
No, because they never reach a player to detonate. The water sweeps them into the drop before they can target you, and the fall kills them. That is exactly why a tower grinder is the safe way to farm gunpowder.