Minecraft Flat World Seed: The Ground Is a String, Not a Number

Three reasons a new code changed nothing

The complaint always has the same shape: the code is supposed to be a village seed, the world loads, and there is no village. The three causes below produce an identical result, which is why they get confused with each other. None of them is the seed.

One: you are on Bedrock

This is the largest of the three, and it is absolute rather than rare. In a flat world on Bedrock nothing generates above the layers you chose: no villages, no strongholds, no mineshafts, no ruined portals, no trees. The preset affects the layers and the biome, and that is the whole of it. So on Bedrock a flat world seed is a setting you can change as often as you like with no visible effect, and a list of flat world seeds for that edition is a list of numbers with nothing behind them.

What proves it: open the same code twice, once as a flat world and once as a normal world. The normal world has a village, the flat one has a plain. That difference is the edition, not the code. Edition gate

Two: the biome in your preset is not one a village accepts

A flat world carries a single biome, and the biome is written into the preset rather than derived from the seed. Villages are biome-bound, and the documented list is short: plains, desert, taiga, savanna, snowy taiga and snowy tundra. Put an ocean or a windswept hills in the biome slot and no seed will produce a village, because the placement check never gets a valid answer. One naming caveat matters: that list was written before 1.18 renamed snowy tundra to snowy plains, so a preset carrying the newer name is the same case as the older one rather than an exception to it.

What proves it: read the second part of your preset code. If it is not one of those six names, the seed was never the problem. Biome gate

Three: the structure switch is off, or the preset never listed structures

Structures in a flat world run through a separate option in the world creation screen, and it has to be switched on. The default is on, which is exactly why people do not remember touching it. Under that switch sits the preset's own list: Classic Flat generates villages and nothing else, a world with no preset selected generates villages and strongholds, and the Overworld preset adds outposts, mineshafts and ruined portals to the plains features. A preset that lists nothing cannot be rescued by any code.

What proves it: the structure list shown on the preset itself, before you type a seed. Preset gate

Only the last row is the situation a seed list is for. The other three are why people conclude that flat world seeds do not work, when the seed was never being asked the question.

Nine presets, and the arithmetic of where you stand

The preset code lists blocks from layer -64 upward, so the number of layers in a preset is also the height of your feet: feet at Y equals -64 plus the layer count. That single line of arithmetic explains why two flat worlds can sit at wildly different altitudes while both being perfectly flat, and it is worth doing by hand before you trust any description of a preset.

Read the last two columns together and the presets sort themselves. Five of the nine can hold a village; three list a stronghold; two list nothing at all; and Water World's structures are all underwater, which makes it a diving world rather than a walking one. The biome column is the reason for most of that sorting: of the nine presets, six distinct biomes appear, and three presets reuse plains.

The layer counts are also a trap for anyone copying a preset description from somewhere else. Classic Flat is four layers and puts your feet sixty-three blocks below sea level; the Overworld preset is sixty-four layers and puts them at zero. Both are flat. They are not the same place, and a slime farm or a mob trap built for one will not behave the same way in the other.

The preset code, read left to right

A preset code has three parts, divided by semicolons. The first is the block list, ordered from layer -64 upward, where a number and an asterisk in front of a block ID means that many layers of it, so two dirt layers can be written as one entry instead of two. The second part is the biome, as a namespaced ID. The third part used to hold feature generation options; it has not been supported since 1.16, and structures were removed from the code as a settable field in 20w21a, which is why the structure list now lives on the preset rather than in the string.

Two more rules are worth knowing before you edit anything. Version numbers inside preset codes were dropped in 17w47a, so a code copied from an older version may carry a field that no longer means what it did. And a code that is formatted incorrectly does not half-work: the game falls back to the Classic preset, which is a silent and confusing outcome if you expected your string to load.

Classic Flat, written out — minecraft:bedrock,2*minecraft:dirt,minecraft:grass_block;minecraft:plains 4 layers Feet at Y -60 Villages only

The same world without a bedrock floor — minecraft:grass_block,3*minecraft:dirt,2*minecraft:cobblestone;minecraft:plains 6 layers No bedrock Void reachable on foot

Desert, with temples and a stronghold on the list — minecraft:bedrock,3*minecraft:stone,52*minecraft:sandstone,8*minecraft:sand;minecraft:desert 64 layers Feet at Y 0 Desert temple

A tall stone world at sea level — minecraft:bedrock,63*minecraft:stone,minecraft:grass_block;minecraft:plains 65 layers Feet at Y 1 Stone to dig

Those three strings are the layer tables above written out in the documented format, not files copied from anywhere; the biome field is plains in all three, so all three are on the village list. If you want a village you cannot get one by editing the seed, but you can lose one by editing the biome — that is the practical difference between the two fields, and it is the whole reason this page exists.

The one grid the seed still owns

Slime chunks are where the seed is still doing real work, and the behaviour differs by edition in opposite directions. On Java, whether a chunk becomes a slime chunk is decided by the seed combined with the chunk coordinates: the two are mashed into a random source, and roughly one chunk in ten comes out as a slime chunk. On Bedrock the algorithm does not use the seed at all, so the same coordinates are slime chunks in every world you will ever open.

Put that next to the layers and one useful consequence falls out. Slimes need a height under Y 40, and Classic Flat puts your surface at Y -60, so in a Classic Flat world the entire plain is inside the spawning band. A slime chunk is not something you find underground there, because there is no underground: the chunk you are standing in either qualifies or it does not, and the answer is a property of your code.

There is a detail attached to this that is easy to miss and hard to guess: the game documents that only the low 48 bits of the seed feed the slime chunk calculation. Two codes that differ only in their high bits can therefore share a slime grid while building different structures. If your only goal is slime, that makes the seed field cheaper than it looks, but the same fact also means a code that is good for slime tells you nothing about where a village went.

Flat, but not empty: what a village needs to stand on

A village is the one structure that a flat world makes strange, because the terrain it normally sits on does not exist. The documented rule is generous: a village does not form in mid-air, but it can form as long as there is at least one solid block layer, and it always spawns at least two blocks above the void. That is why Bottomless Pit, six layers with no bedrock under it, still holds villages, and why The Void, one layer of air, holds nothing.

The other half of the rule is that most structures need suitable terrain to appear on or in, while mineshafts and strongholds are the exceptions that do not. In practice that means a flat world can produce a stronghold on a preset that lists strongholds even when the layers give it almost nothing to work with, and it means a desert temple needs a desert preset because the biome is doing the work rather than the ground.

This is also why the two parts of a flat world are worth judging separately. The layers decide whether a structure can sit somewhere; the seed decides where it sits within the allowance. A page that lists flat world seeds without telling you which preset it used has thrown away the half of the answer that was actually written down.

Five checks that tell a seed problem from a preset problem

Run these in order. Four of the five cost nothing, and the first one that fails is the answer; there is no point opening a second world until you have been through them.

What check five looks like in practice: create two worlds on the same preset with different codes, and note the direction of the first village from spawn in each. If the two directions differ, the seed is doing its job and the code you were using is simply not a village code for that preset. If both worlds are empty, go back to checks one through four, because the seed has already been proven innocent.

There is a reason this page does not hand you a list of flat world codes to try. On Bedrock such a list cannot work, and on Java it only means something alongside the preset and the structure switch it was recorded on — three fields, of which most lists publish one. A code without those two fields is a number, not a seed. If you want the same discipline applied to normal worlds, the Bedrock checklist and the Java checklist are built around exactly that idea.

The first day on a flat world

Classic Flat is the version worth planning for, because it is the preset most people mean by the phrase and the one with the least to work with. Four layers, no trees, no caves, one biome, and villages as the only structure the preset lists.

Two notes that save a run. First, slimes: on a Classic Flat world your whole plain sits inside the slime height band, so a qualifying chunk will produce them at surface level, and a night in the open is a night among them. Second, edges: Bottomless Pit has no bedrock layer at all, so the familiar assumption that the world has a floor does not hold, and a fall out of it is not recoverable by digging down.

If you are running the world with other people, the host matters more than the preset: Shockbyte is a low-cost Minecraft host that is set up in minutes, and code LAUNCH takes 25 percent off the first month. If you sign up through that link I may receive a commission at no extra cost to you, and it does not change what you pay. Whatever host you use, the flat world flag goes in the server properties file: level-type=minecraft:flat on Java, and FLAT as the value on Bedrock.

If what you actually wanted was a thin world with something in it rather than an empty plane, the floating island page covers terrain that is small without being featureless, and the skyblock page covers the version where the smallness is the point.