Terraria server RAM: vanilla to Calamity

A vanilla Terraria server needs 512 MB to 1 GB of memory for a small or medium world with up to four players, and about 1 GB for a large world with eight. TShock with a stack of plugins, or a vanilla server pushed to sixteen players, is comfortable at 2 GB. tModLoader changes the answer completely: 2 to 3 GB for a handful of quality-of-life mods, 4 GB for Calamity with its usual companions, and up to 6 GB at peak for large content packs that add their own world generation. The peak is the important word. A Terraria server reaches its highest memory use when it creates a world, not when people play in it, which is why the first modded world on an undersized plan is the one that fails.

What a Terraria server holds in memory#

Terraria is unusual among sandbox games in one respect that decides its sizing: the server loads the entire world into memory and keeps it there. There is no chunk loading and unloading as players move. Every tile of the map, every wall, every liquid, every chest and every sign is resident from start to shutdown.

That makes the world size the first input, and it is a known number:

A large world holds four times the tiles of a small one, and the tile data is the bulk of a vanilla server's memory. That is why world size moves the vanilla figure more than players do.

The rest of vanilla memory is bounded in a way most games are not. Terraria stores active NPCs, projectiles and dropped items in fixed-size tables - 200 NPCs, 1,000 projectiles, 400 items at once - and a world can hold at most 8,000 chests. Memory for those does not grow when an invasion fills the screen; CPU does. The things that do grow are player connections and their buffers, and on tModLoader everything the mods add.

RAM by world, players and server type#

Those figures agree with the longer Terraria and tModLoader server guide, which also covers installation. Two things are worth drawing out.

Players are cheap. The default maxplayers is 8 and the setting accepts up to 255, but each extra player adds network buffers and a little state, not a slice of the world - the world is already fully loaded. What more players change is CPU during events, when the server updates every NPC and projectile on one thread.

Modded servers are a different category. A Calamity server for four people uses several times what a vanilla server for sixteen does, and the gap is entirely the mods.

The world size setting#

World size is chosen once, at creation. On a dedicated server it is the autocreate value in serverconfig.txt, used when the named world does not exist yet:

world=/home/container/worlds/Hallowed_Acres.wldautocreate=3worldname=Hallowed_Acresdifficulty=1maxplayers=8port=7777password=change-mesecure=1npcstream=60

autocreate=1 is small, 2 medium and 3 large. difficulty is 0 classic, 1 expert, 2 master and 3 journey. npcstream reduces how often enemies appear to skip across the screen for players; lowering it smooths movement at the cost of a little more bandwidth, and it does not change memory. Terraria server config and commands goes through every key.

Large is the right choice for a group of six to eight who want room, and the memory cost over medium is a few hundred megabytes on vanilla. For a group of two or three, medium plays better and costs less. On modded servers the choice matters more, because content mods add biomes, structures and ores to every world, and their generation passes scale with world size.

World generation is the peak#

When a Terraria server creates a world, it builds the whole thing in memory through dozens of generation passes - terrain, caves, biomes, ores, structures, dungeons, temples, chests and their loot - and only then writes the .wld file. During that process it holds working data on top of the world itself. On vanilla the overhead is modest. On tModLoader, every mod that adds generation passes adds its own working data, and large content mods add many.

The consequences:

1. A plan that runs a world can fail to create it. If the server is stopped partway through generation, look at memory before anything else.
2. Generation takes longer than people expect. A large modded world can take several minutes. Watch the console percentages rather than assuming it has hung.
3. There is a cheap way round it. Generate the world in the game client on your own PC, with exactly the same mods and versions, then upload the .wld file (and its .twld companion on tModLoader) to the server. The server then only has to run the world, never build it.

tModLoader: what mods cost#

tModLoader runs mods inside the server process on a modern .NET runtime. A dedicated server skips most graphics work, but it still loads every mod's code, registers its items, NPCs, tiles, projectiles and buffs, and holds whatever state the mod keeps. Costs differ widely by type.

• Quality-of-life mods - magic storage, recipe browsers, boss checklists, auto-trash - add little each. Magic Storage is the exception that grows: it holds a lot of items in one system, and a server's whole hoard ends up in it.
• Content mods add hundreds or thousands of new items, enemies and tiles. Calamity is the reference case; Thorium and similar packs behave the same way.
• Companion and add-on mods for the big content mods add their own content on top.
• Worldgen mods add structures and biomes, and their cost lands mostly at creation.

The practical workflow:

1. Pick the mod list and versions with the group before starting, and keep server and clients on exactly the same list.
2. Start the server once with nobody online and note idle memory after the world loads. That is your floor.
3. Generate the world or upload one generated locally.
4. Watch memory during the first boss fight with everyone online. Floor plus that spike plus a margin is your plan.

Calamity and large mods on a server covers installing the big packs and keeping clients in sync.

TShock and plugins#

TShock is a server-side framework for vanilla Terraria that adds user accounts, groups and permissions, region protection, anti-cheat checks and a large set of admin commands. It runs on the vanilla server and keeps its data in a database, SQLite by default. Clients need nothing.

Its memory cost is modest: the framework, its database connection, and whatever its plugins hold. Plugins that log every tile change, track statistics or run minigames hold more. A TShock server with a dozen plugins sits comfortably at 2 GB for most communities. It also gives you admin tools vanilla lacks - /butcher to clear hostile NPCs after an event goes wrong, for example - which is useful for CPU problems rather than memory ones. The TShock server guide covers setup and permissions.

One world per server#

A Terraria server process runs one world at a time. That surprises groups who want a main world plus a separate world for farming, a Hardmode test world or a boss rush, and it has a direct effect on sizing.

There are two ways to run several worlds:

1. One server, switch worlds. Stop the server, change world= in serverconfig.txt to the other .wld file, and start it again. Memory stays the same as for one world - only one is loaded - but nobody can be in both at once, and switching takes a restart.
2. Several servers. Run a separate server per world, each with its own port and its own memory. Every one carries the whole of its world in memory, so two large vanilla worlds need roughly twice the memory of one, and two Calamity worlds need twice the modded figure.

For most groups the first option is right. A world nobody is playing in does not need to be running, and the Terraria client lets players move their characters between worlds freely - characters are stored on each player's machine, not on the server, unless the server enforces server-side characters through TShock.

That last point matters for sizing too. Server-side characters in TShock store each player's inventory in the server's database rather than on their machine, which adds a little memory and disk per player and makes the server responsible for backing up characters as well as worlds. For an anti-cheat-minded public server it is worth it; for friends it is usually unnecessary.

On tModLoader, every world on a server shares the same enabled mod list, because mods are loaded per server process, not per world. A group that wants a vanilla world and a Calamity world needs either two servers or a change of enabled.json and a restart between them.

CPU, events and what is not a memory problem#

Terraria's lag usually comes from CPU during events, not from memory. The server updates every active NPC and projectile each tick on one thread, and a Frost Moon with sixteen players present, a boss with a screen full of projectiles, or a modded boss with hundreds of them is a heavy few minutes. Memory sits flat while it happens, because those tables are fixed in size.

So when players report lag:

• During invasions, bosses and events, it is CPU. A higher tier helps if the CPU graph is flat at its limit; fewer simultaneous events and fewer farms with dozens of statues help in any case.
• All the time on a modded server, check whether memory is near the limit and the runtime is collecting constantly. That is a plan that is too small for the mod list.
• Only for one player, it is that player's connection.

CPU or RAM: which one is holding your server back covers reading the graphs, and how many players fit on a server covers why slot counts promise less than they seem to.

Saves, backups and memory stops#

The server autosaves periodically and saves on a clean exit. The vanilla console's save command forces a save at any time. Anything that ends the process without a save - a host reboot, a kill, a memory stop - loses whatever happened since the last write.

A Terraria world is one file (two on tModLoader), so a corrupt write damages the whole world rather than a region. Keep backups somewhere other than the server's own folder, and take one before every update and every mod change. Terraria world backup and transfer covers the files and the restore.

On RE:NODE a server that reaches its memory limit is stopped and restarted clean rather than left to swap, which is safe for the machine and loses unsaved progress, so leave a margin on a modded server rather than running it at the edge. Terraria plans run from 512 MB at $3 a month up to 4 GB, with one port allocation and backup slots on every tier. Moving up a tier raises the limit on the server you already have, so a world that outgrows its plan stays where it is.

FAQ#

Is 1 GB enough for a Terraria server?

For vanilla, yes, up to a large world with about eight players. TShock with several plugins, or sixteen players and frequent events, is more comfortable at 2 GB. Any tModLoader server beyond a couple of small mods needs more.

How much RAM does a Calamity server need?

Plan on 4 GB for Calamity with its usual companion mods and a handful of players. The peak is world generation; if you generate the world on your own PC and upload it, the server only needs enough to run it. Larger packs with their own worldgen can peak around 6 GB.

Does a large world use more RAM?

Yes. The whole world is held in memory, and a large world has four times the tiles of a small one. On vanilla the difference is a few hundred megabytes; on modded servers it is larger, because mods add content to every part of the map.

Why did my server stop while creating a world?

Almost always memory. World generation peaks well above the memory needed to run the finished world, especially with mods that add structures and biomes. Generate the world locally with the same mods and upload the .wld and .twld, or create it on a larger plan once.

Do more players need more RAM on Terraria?

A little. The world is already fully loaded, so each player adds connection state rather than terrain. More players mostly change CPU during events and bosses, when every NPC and projectile is updated on one thread.