RAM is the setting people reach for first when a server struggles, and it’s usually the wrong one. Memory is not a speed dial: past the amount a server actually needs, adding more does nothing for performance and can even hurt. Here’s how much different servers really want, and how to tell whether RAM is your problem at all.
Rough numbers by server type
- 1Vanilla or lightly-plugged Paper, a few friends: 2-3 GB is plenty.
- 2A busy Paper server with many plugins and 10-20 players: 4-6 GB.
- 3A small/optimised modpack (Fabric performance packs): 4-5 GB.
- 4A medium modpack (100-ish mods): 6-8 GB.
- 5A large content modpack (200+ mods, like Better MC): 8-12 GB or more.
What actually drives the number
Two things dominate. Mods and plugins: each loads data and systems into memory, so a 300-mod pack needs far more than vanilla before a single player joins. And loaded chunks: more players, and higher view/simulation distance, mean more of the world is held in memory at once. A server’s real appetite is roughly "base cost of its mods/plugins" plus "world kept loaded for its players".
Why more isn’t better
Java cleans up unused memory with a garbage collector, and the bigger the pile it has to sweep, the longer an individual cleanup can pause the game. Give a small server 16 GB and you don’t get a faster server - you get occasional longer stutters when the collector finally runs. The goal is "enough headroom that it isn’t constantly collecting", not "as much as possible". Levyathan already launches servers with tuned G1 garbage collection, so your job is just to pick a sane size.
Is RAM even your problem?
Usually not. Low TPS - the laggy, everything-slows-down kind - is almost always CPU work: too many entities, high simulation distance, heavy redstone. Adding RAM won’t touch it (see the performance guide). RAM is your problem when you see memory-specific symptoms: the console logs OutOfMemoryError, or the server is killed for exceeding its limit, or it garbage-collects so often it can’t keep up. If you’re not seeing those, spend your effort on simulation distance and entities, not gigabytes.
On the free tier
Levyathan’s free tier gives you up to 4 GB across your servers - comfortably enough for vanilla and plugin servers and for lightweight/optimised modpacks. Big kitchen-sink modpacks that want 8 GB+ simply won’t fit there; pick a pack that advertises itself as lite, or size accordingly.