Quick answer: give an RLCraft server 5GB to start, 6GB for a regular group and 8GB for a public server. The pack's author asks players to give the game 3 to 4GB, and a server needs that plus memory for Java itself. RLCraft is lighter on RAM than most modern modpacks, but it makes up for that with heavy entity and structure generation.
RAM by group size
| Group | RAM | Our plan |
|---|---|---|
| A few friends | 5GB | MC Gold |
| A regular group | 6GB | MC Lapis |
| Bigger group or public server | 8GB | MC Diamond |
| Busy public server | 12GB | MC Special 1 |
RLCraft publishes no player counts for servers, so these sizes go by group rather than by an exact number of players. 5GB holds the 4GB heap the pack's author uses with about 1GB left for Java, and 6GB leaves 2GB. The only player figure in the pack's server notes is about the world, not RAM: once more than 10 players will play, pre-generate it first.
Why RLCraft still lags on "enough" RAM
Memory is not RLCraft's real bottleneck. The mod that causes the most performance issues is Lycanites Mobs, which spawns custom creatures far more aggressively than vanilla Minecraft, along with dungeons that generate on the fly. This creates CPU tick lag long before you run out of memory. If your server is lagging with plenty of RAM free, the fix is usually:
- Lowering
"Weight Scale"inconfig/lycanitesmobs/spawning.cfg(0.5 halves Lycanites spawns compared with other mobs) - Reducing view distance to 8, or 6 at the lowest (the pack's server notes say not to go below 6)
- Pre-generating the world so chunk generation isn't happening live during play
Don't over-allocate
A common mistake is setting -Xmx far above what RLCraft actually uses. Over-allocating RAM to an old 1.12.2 modpack can actually hurt performance, since Java's garbage collector has to manage a larger heap even when it's mostly empty, leading to longer GC pause spikes. Match your allocation to the table above rather than assuming "more is always better."
Picking a plan
Our RLCraft server hosting page has these plans with current prices for every region. We suggest MC Lapis (6GB) for most groups; move to MC Diamond (8GB) when the server goes public, and to MC Special 1 (12GB) when it gets busy.
For the full installation and difficulty tuning walkthrough, see the RLCraft server setup guide.