Valheim world size mods: Expand World Size and Better Continents

A vanilla Valheim world is a disc 10,000 metres in radius with a 500-metre edge beyond it, and every seed is a different view of the same fixed layout. Two mods change that. Expand World Size (JereKuusela) changes the numbers: radius, stretch, altitude, water depth, forest amount, how many locations are placed. Better Continents replaces parts of the generator with noise layers and image maps, so you can draw the heights, biomes and start position yourself. Both have to be installed, at the same version, on the server and on every player's PC, because Valheim generates terrain on the client. Both are for new worlds. Point them at a world you have played for months and the ground moves under your buildings.

This guide explains why that is, what each mod changes, the settings that matter, how to generate a world with them and get it onto a dedicated server, and what a bigger world costs.

How Valheim builds a world, and why it matters here#

Three things make a Valheim world, and they are stored very differently.

1. The base terrain - heights, biomes, where land and sea are - is not saved anywhere. It is calculated from the seed by the world generator every time a zone loads. Your .db file does not contain the shape of the ground.
2. Terrain edits - everything players dug, raised or flattened - are stored in the world as changes relative to that calculated ground.
3. Objects - trees, rocks, pickables, creatures, dungeons, boss altars and every piece players built - are stored in the world once their zone has been generated. Locations (altars, villages, crypts, the trader) are placed for the whole map when the world is created, and that placement is saved too.

So a mod that changes the generator changes item 1 for everyone running it, while items 2 and 3 stay exactly where they were saved. That single fact explains all of the rules below: why clients need the mod, why existing worlds break, and why world creation takes longer with a bigger map.

It also explains the zone model. The world is divided into 64-metre zones, and each one is simulated by the first player who walks into it. That player's game generates the terrain for it. If their generator differs from everyone else's, they are walking on a different world.

Expand World Size: the settings that matter#

Expand World Size has to be installed on all clients and on the server. Its settings are saved into the world file when the world is saved, and applied when the world loads, so different worlds keep their own settings; new worlds take whatever is in the config at that moment. Only non-default values are stored.

The README gives the altitude formula as water level + (altitude - water level) * multiplier + delta, with water level at 30 metres. Altitude also drives biome placement - raise it and you get more mountains - while snow by altitude is hard-coded and does not follow.

The size settings interact in ways that catch people:

• Area grows with the square of the radius. Doubling the radius to 20,000 metres gives four times the area. The README's advice is to scale Locations with the area - four times as many for double the radius, sixteen times for four times the radius. If you do not, the extra land has almost no dungeons or altars in it.
• Stretch is the gentler option. Stretch world 2 with Stretch biomes 0.5 keeps the familiar layout, bigger, with biome patches back near their normal size.
• Bigger maps take longer to draw. The map is generated as a background task, shown by a small Loading text. The README's examples: about 15 seconds at the default size, 1 minute at size 2, 4 minutes at size 4, 16 minutes at size 8 and an hour at size 16. ew_map regenerates it manually.
• There is a save-format limit. Valheim saves the world in chunks that cover a radius of 16,384 metres; anything beyond lands in one chunk and causes heavy lag. Expand World Size enlarges the save grid automatically (up to a 65,536-metre radius) and converts the save on load. The README is explicit: do not load or save a world bigger than 16,384 metres without the mod, or objects can be duplicated.

It also has Offset X and Offset Y, which move your world within Valheim's larger fixed layout, Seed to replace the seed outright (saved permanently), and ew_seeds to print the current offsets and seeds. Settings for the Ashlands and Deep North terrain exist as well; if you also run Expand World Data, change those in only one of the two mods.

Better Continents: drawing the world#

Better Continents works at a different level. Instead of scaling the vanilla generator, it gives you its own: a layered noise system with separate distortion and masks per layer, presets, and an in-game interface for designing a world with a live map. On top of that you can feed it image files - a heightmap, a detail map, a biome map, a spawn map for locations such as the start altar, bosses and the trader, and a forest map. Global options include continent size, sea level, forest scale and an explicit start position. It can export the full map to PNG at any resolution, and it still loads vanilla worlds normally.

A Better Continents world is three files rather than two: the usual Name.fwl and Name.db plus a file ending in .BetterContinents beside them, which holds the settings and image data. The extra file has to travel with the world. Its documentation states that client and server need the same version of Better Continents when running a Better Continents world, while players can still join vanilla servers with it installed.

Check the package before you commit a group to it. The original Better Continents by billw2012 has been marked deprecated on Thunderstore since its last update in 2022, and a later fork by JereKuusela is now deprecated too. At the time of writing a maintained fork is published by Wubarrk, with recent updates. Read its changelog for the current Valheim version, and remember that a long-term world depends on that fork staying maintained. Better Continents worlds built from image maps can also be very large on disk - map authors on Nexus sometimes warn that their worlds are hard to run on a server - so look at the file size before you upload someone else's map.

Why existing worlds suffer#

Go back to the three layers. When you change world size or generator settings on a world that already exists:

• The ground changes under saved objects. Trees, rocks and every player building were saved at fixed heights. If the new generator puts the ground ten metres lower, the longhouse floats; if higher, it is buried. Expand World Size's README warns that some settings change terrain enough to destroy buildings.
• Terrain edits are relative. A flattened base was stored as a change to the old ground. Applied to new ground, it can leave a pit or a plateau where the base used to be.
• Biomes shift but vegetation does not. A zone generated as Black Forest keeps its pine trees and Greydwarf spawners even if the new layout calls it Meadows.
• Locations were already placed. Locations are decided at world creation. Enlarge the radius and the new outer ring has none until you run the vanilla genloc devcommand, which places what could not be placed before.
• Seams appear. Zones nobody visited will generate with the new rules, next to zones generated with the old ones.

The only safe change to a lived-in world is one that does not touch explored land - and few settings work that way. Radius alone comes closest: increasing it leaves the inner map's terrain alone and only adds land outside the old edge. Even then, run genloc, back up first, and check the log.

If your real goal is "our world is used up and we want new land", look first at Valheim old worlds and new biomes and the Upgrade World mod, which regenerates zones and locations inside vanilla's generator, or start a fresh world and keep characters as described in resetting a world without losing characters.

Generating a new world and putting it on a server#

The cleanest path is to make the world on a PC, check it, and upload it.

1. Install the mod, at the version the server will run, in a mod manager profile. Make sure the same profile is what your group will use - r2modman profiles for a group shows how to share one.
2. Set the config (Expand World Size) or design the world in the in-game interface (Better Continents) before creating the world. For a seed, the Valheim seeds guide has the checks for a good start area.
3. Create the world in single player, wait for location placement to finish, and look at the map. With Expand World Size, ew_seeds confirms what you made.
4. Close the game so the world is saved, then find the files in worlds_local.
5. On the server, install BepInEx and the same mod version, stop the server, upload the files and set the world name to match. Uploading a local world has the exact steps.

worlds_local/  Midgard.fwl  Midgard.db  ...BetterContinents          Better Continents worlds only: upload it too

Generating directly on the server also works: install the mod, set the config, and start with a -world name that does not exist yet. The first start takes much longer than usual on a large world, because locations are placed across the whole map. Watch the console until the world is loaded before anyone joins, and do not restart halfway through.

What a bigger world costs#

A large map does not cost what people fear, and costs what they forget.

• Memory follows exploration, not radius. The server holds what has been generated and built. A 20,000-metre world that has been explored as much as a vanilla one uses similar memory. A world your group explores aggressively for months grows its .db with every zone visited.
• World creation is slower. More locations to place means a longer first start, and the README warns that a high Locations multiplier can increase it significantly.
• Saves get longer. A bigger .db takes longer to write, which is the hitch players feel at every save interval.
• Travel takes longer. This is a gameplay cost. Ore runs and boss trips stretch with the distances, which makes portal rules a bigger decision than usual.
• Clients pay for map generation. Larger minimap sizes take minutes per client to draw.

On RE:NODE, memory and disk are the plan's ladder, from 2 GB and 15 GB on Starter to 8 GB and 50 GB on Premium. A modded world on a big map is a reasonable case for the middle of that range, and if it outgrows the plan, moving up a tier changes the limit on the same server without moving the world. For the general picture of where server load comes from, see Valheim server performance and lag.

Keeping a modded world playable#

A world made with a generator mod depends on that mod for the rest of its life. A few habits keep it alive:

• Pin the version. Do not let the server or a player update the mod on its own. A changed default in a new version changes the terrain for that player.
• Keep the config with the backups. Expand World Size saves settings in the world, but keep a copy of the config file anyway. For Better Continents, the .BetterContinents file is part of every backup - a backup without it is unusable.
• Update after the mod does. On a Valheim patch day, wait until the mod supports the new version and test on a copy of the world first. After a game patch walks through the routine.
• Read the BepInEx log on first start. Version and config errors show there long before anyone notices strange terrain. BepInEx log troubleshooting covers what the lines mean.
• Crossplay is out. Xbox players cannot install mods, and a player without the generator sees different terrain from everyone else. Treat these worlds as PC-only - see crossplay and Xbox players for what crossplay requires.

On RE:NODE, backups are stored off the machine they protect and can be downloaded, so it is easy to keep a known-good copy of the world, its .BetterContinents file and the mod config on your own PC as well.

FAQ#

Can I make my current world bigger without starting over?

Partly. Increasing only the radius with Expand World Size adds new land outside the old edge and, in principle, leaves the explored map alone; then run genloc to place locations in the new area. Back up first and inspect your bases afterwards. Other settings - stretch, altitude, biomes - reshape explored land and are only safe on a new world.

Do players without the mod see the same world?

No. Their game generates vanilla terrain from the seed, so they see saved buildings and trees sitting on ground that does not match. Everyone, server included, needs the mod at the same version and settings.

Does a 20,000-metre world need four times the RAM?

No. Memory grows with what has been generated and built, not with the size of the map on paper. A bigger map lets that grow further over time, and makes the first world creation slower.

Can I use Expand World Size and Better Continents together?

They both change world generation, and some settings overlap. Use one generator mod per world unless both mods' current documentation says the combination is supported, and test it locally before putting a group on it.

What happens if the mod stops being updated?

The world keeps working on the last game version the mod supports, and nowhere else. That is the real risk with generator mods, which is why maintenance status matters more here than for a quality-of-life mod.