Middle-ground iron farm (the most iron for an evening's build)

441 iron an hour · 615 blocks · 0.72 an hour per block · 16 iron to build · golems fall out of sight to a lava blade

Villagers scared by a zombie summon iron golems; the farm kills them and collects their iron in a chest.

440 iron an hour on a rainy day, 439 in a thunderstorm. Nether quartz: 3; iron: 16. Fits in 2 chunk columns: 11×27×17. Restarts by itself when you come back after days away. Its storage holds 4 hours of iron.

441 iron an hour from a 27-minute build

441 iron an hourIron farm3D view loading (or not available in this browser)

Try it

Press play to watch it work: the villagers sleep at night and panic at the zombie by day, golems spawn and die, and the hoppers carry their iron to the chest; the top right counts the game's time, the golems and the iron. The magenta floor is where a golem can spawn, seen through the blocks (Spawn spots hides it). The chest tagged OUT, under the last hopper, collects the iron. In the game, build it and wait near it.

How this design does it: Golems fall out of sight to a lava blade.

Build it

Download .litematic Download the design as text

The .litematic opens in Litematica (Minecraft 26.3): every block of the design in one region. The text file is the same build written as plain text, block by block.

Pour in the water and the lava (4 bucketfuls) where the view shows them.

Blocks used: chest cobblestone cobblestone slab comparator hopper lava oak boat oak fence gate oak trapdoor observer red bed redstone wire repeater torch villager water

What it is made of

Each part of this farm, what it takes to build, and the version of it this farm uses: follow a part to see its other versions side by side.

part	this farm's	blocks placed	blocks dug	build time
Villager cage	its own · other versions	75	94	15 min
Sleep trigger	its own · other versions	17	0	2 min
Golem spawn area	its own · other versions	25	0	1 min
Golem drop	its own · other versions	23	293	4 min
Kill chamber	its own · other versions	12	68	2 min
Collection	its own · other versions	3	0	2 min
At the farm's spot	25 cobblestone slabs capping stray golem spots and 1 glass caps in water and 20 cobblestone seals	51	270	counted above
The whole farm		206	725	27 min

Details: how it works, measurements and properties

In depth

villagers scared by a zombie summon iron golems; the farm kills them and collects their iron in a chest

How to try it

Press play to run the farm. The villagers sleep in their beds at night and panic at the zombie by day, golems spawn, fall and die in the lava, and the hoppers carry their iron and poppies to the chest. The chest tagged OUT, under the last hopper, collects the iron. The top right shows the game's time, the golems so far and the iron in the chest; the speed menu plays it faster or slower. Drag to look around, pinch or scroll to zoom.

Measurements

On Hard, through rain, thunder and lightning.

metric	value	what it means
iron per hour per block	0.72	iron ingots an hour for each block you place
iron per hour	441	iron ingots an hour
iron range	95% 438-445	the range its rate falls in, 95% sure
golems per hour	110.6	iron golems an hour
seconds per golem	32.6	the time between two golems
share of ceiling	92%	how close it comes to the game's limit: one golem every 30 seconds for each group of villagers
modules	1	groups of villagers that each summon golems on their own
iron per hour per module	441	iron ingots an hour for each group of villagers
kill	17.1 s	how long a golem lives before the farm kills it, at the longest
kill tail	the longest 20.75 s: no golem outlived 1 min in 11,793 golems (95% bound 0.03% a golem)
golems at the zombie	0 of 11,793 golems targeted the farm's zombie
lips	none (no golem stands dry beside a current)
restarts after a missed night	yes	whether it starts again by itself after a night its villagers could not sleep (rain at dusk, a storm, you away)
restarts after days away	yes (unloaded or not ticking	whether it starts again by itself when you come back after days away
back	by day or at night: the first golem 0.0-0.1 h after the return)
rain	clear day 441 iron/h; rain day 440 iron/h; thunder day 439 iron/h	iron an hour on a clear day, a rainy day and a stormy day
lightning	about 0.0 iron lost per thunderstorm; no villager ever turned into a witch; the zombie's boat broken never; a fire that can reach the farm (its flammable blocks or mobs or drop path) never; site note: a fire on the site that cannot reach the farm about every 12 game days; AFK spot struck: about every 15,946 game days (a 7 x 7 opaque non-flammable roof over the player's column with its block 4 above the player's feet prevents it: a single block over its column does not); no natural flammable block lies on a fire's way to the farm; a skeleton trap horse on the farm about every 585,451 game days (every 8,366 game days of thunder; a lightning rod topping its column within 128 blocks prevents it); a skeleton trap horse that triggers (within 10 blocks of the AFK spot) about every 3,996 game days (a lightning rod within 128 blocks topping its column takes the bolts: none then); lightning never breaks the farm; thunderstorms 1.4% of the time (5 min 10.55 s each on average)	what thunderstorms cost: the iron a strike burns, and how often a strike turns a villager into a witch, breaks the zombie's boat or starts a fire
thunder loss	0.0	iron lost for each hour of thunder
sunburn	never (the zombie never sees the sky)	whether the zombie can burn in daylight
fire	never	whether the lava can set the farm on fire
bill	16 iron, 3 quartz, 4 villagers, 4 beds, 1 zombie	what it costs in survival: iron (hoppers, the bucket and every tool you need), quartz, villagers, beds
payback	2 min	how long the farm takes to make back the iron it cost
build time	27 min at day-1 prices (206 placed with 25 cobblestone slabs capping stray golem spots and 1 glass caps in water and 20 cobblestone seals, 725 dug (the stair down to the chest: 96 dug, 5 placed), 1 lava trips, 4 villagers moved; the most: 4 villager_moved 480 s, 725 dig 362 s, 206 place 206 s, 1 zombie 120 s, 2 hopper 104 s, 1 lava_trip 60 s, 196 travel:stairs 49 s, 4 red_bed 39 s)	about how long the build takes: placing and digging its blocks, fetching the lava, moving the villagers in
time to an iron kit	30 min at the cheapest spot (from dawn of day 1 until the chest holds 24 iron; runs 30-31 min; 30-32 min over the 12 nearest spots)	about how long from starting the build to a full set of iron armour (24 iron), its own iron counted
build minutes	26.6
t kit minutes	30.3
collecting	16 s per trip to the chest (2 x its depth, 33 layers
at	the access's speed)
iron per hour sleeping	449
volume per module	5,049
entities alive	6.6
entities peak	8
tools	bucket 3 + iron pickaxe 3	the tools you need and the iron each one costs: a bucket for lava and water, shears for leaves, an iron pickaxe for redstone dust
lava sources	4	lava source blocks to bring: one bucket trip each
materials	Nether: quartz in 3 blocks	the stage of the game its materials need: day 1, the Nether (quartz, slime, magma...) or the End
chunk columns	2	how many 16 x 16 chunk columns it covers
storage	4.1 h (37 slots; 110 poppies/h)	how long its chests and hoppers hold the iron and poppies before they fill
hoppers per 1000 iron/h	4.5	hoppers for each 1000 iron an hour: each hopper costs the server a little work every tick
spot	plains at -289 63 231 (the cheapest of the 12 nearest valid spots)
exposures	in plains (-289,231): C2 entry baby zombie 127 cells
bat	536
cave	spider 148
fox	148
slime	149; C3 sight baby zombie 20 cells; C4 presence village villager 643 cells
village	golem 505; C5 reach baby zombie 46 cells
baby	zombie 4
cave	spider 67
pillager	7
skeleton	7
slime	83
zombie	7; C6 pickup village villager 9 cells; C8 creepers creeper 21 cells
creeper	44; C9 endermen an enderman 11 cells
build minutes	flat 26.6
villagers	left 0
hostile	break days exposed: C2 entry; C5 reach; C8 creepers; C9 endermen
redstone dust	26	the redstone dust its blocks take to craft (a repeater or a comparator 3, an observer 2, a piston 1...): redstone ore needs an iron pickaxe to mine

Properties

Study	Mob farms
Kind	Middle-ground iron farm (the most iron for an evening's build)
Blocks placed	615
Box	11×27×17 (5049 blocks of space)
Works facing any way, anywhere	no: locational, it depends on where it is built
Inputs / outputs	no input / OUT
Flags	variation
Design file	`module-underground`

The design file

on GitHub

Design file (533 lines)

# Iron farm: 441 iron an hour · 615 blocks · 0.72 an hour per block · 16 iron to build · golems fall out of sight to a lava blade
# https://vjeux.github.io/redstonepedia/farms/iron/module-underground.html
# CIRCUIT: seconds per golem 32.6
name: iron-module-underground
afk: 1 9 0
circuit: mob-farm iron_ingot
ground: 8
how: golems fall out of sight to a lava blade
parts: hide off-delay-ring-L24 + a repeater
restart: yes
sample: plains
terrain: rock
port output: 3 -24 1
entity: minecraft:villager 0.5 0.5625 0.5
entity: minecraft:villager 2.5 0.5625 0.5
entity: minecraft:villager 4.5 0.5625 0.5
entity: minecraft:villager -1.5 0.5625 0.5
entity: minecraft:oak_boat 2.5 0.5 -6.8 {Passengers:[{id:"minecraft:zombie"}]}
origin: -4 0 -8
palette:
  A minecraft:air
  B minecraft:cobblestone_slab[type=bottom,waterlogged=false]
  C minecraft:chest[facing=north,type=single,waterlogged=false]
  D minecraft:comparator[facing=east,mode=compare,powered=false]
  E minecraft:comparator[facing=north,mode=compare,powered=false]
  F minecraft:oak_trapdoor[facing=north,half=bottom,open=false,powered=false,waterlogged=false]
  G minecraft:oak_trapdoor[facing=south,half=bottom,open=true,powered=false,waterlogged=false]
  H minecraft:hopper[enabled=true,facing=down]
  I minecraft:observer[facing=south,powered=false]
  J minecraft:redstone_wire[east=none,north=none,power=0,south=side,west=none]
  K minecraft:redstone_wire[east=none,north=none,power=0,south=side,west=side]
  L minecraft:lava[level=0]
  M minecraft:redstone_wire[east=none,north=side,power=0,south=none,west=side]
  N minecraft:redstone_wire[east=none,north=side,power=0,south=side,west=none]
  O minecraft:oak_fence_gate[facing=east,in_wall=false,open=true,powered=false]
  P minecraft:redstone_wire[east=side,north=none,power=0,south=none,west=side]
  Q minecraft:redstone_wire[east=side,north=side,power=0,south=none,west=none]
  R minecraft:red_bed[facing=north,occupied=false,part=foot]
  S minecraft:redstone_wire[east=side,north=side,power=0,south=side,west=side]
  T minecraft:repeater[delay=1,facing=west,locked=false,powered=false]
  U minecraft:repeater[delay=2,facing=south,locked=false,powered=false]
  W minecraft:water[level=0]
  c minecraft:cobblestone
  h minecraft:hopper[enabled=true,facing=east]
  o minecraft:oak_fence_gate[facing=north,in_wall=false,open=true,powered=false]
  r minecraft:red_bed[facing=north,occupied=false,part=head]
  t minecraft:torch
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