The most common question the observatory receives, by a comfortable margin, is some form of “how much RAM do I actually need?” The honest answer is that it depends on three things: how many players you expect, how far they wander, and what you have bolted onto the game. Everything else is detail.
The short table
| Configuration | Players | RAM |
|---|---|---|
| Vanilla survival | 2–10 | 4 GB |
| Paper + 20–40 plugins | 10–30 | 8 GB |
| Light modpacks (Fabric + performance mods) | 5–20 | 8 GB |
| Heavy modpacks (All the Mods, RAD) | 5–30 | 16 GB |
| Large SMPs with big view distances | 30+ | 16 GB |
Why players matter less than you think
A common surprise: ten players standing in one town cost far less than three players exploring in three directions. Chunk generation is the hungriest thing a Minecraft server does — each explorer forces the server to generate, light, and hold new terrain. If your community loves 10,000-block journeys, budget as though you had triple the player count.
Why modpacks change everything
Vanilla Minecraft is disciplined about memory. Modpacks are not. Every machine humming away in a base, every custom dimension, and every pipe network stays resident in memory whether anyone is looking at it or not. A 40-player Paper server can be happy on 8 GB while an 8-player All the Mods world gasps on the same allocation. When in doubt with a heavy pack, take the 16 GB — an out-of-memory crash mid-boss-fight costs more goodwill than the upgrade costs money.
Three signs you need more memory
- Save stalls — the world pauses for a second or two at regular intervals as the garbage collector fights for its life.
- Falling TPS with normal CPU — ticks drop below 20 while the processor looks bored; the server is thrashing memory, not computing.
- Crash logs mentioning
OutOfMemoryError— the least subtle sign, usually arriving at the worst moment.
A note on “more is always better”
It is not, quite. Java’s garbage collector can develop longer pauses with enormous heaps it never fills. Matching the allocation to the world is the craft: 4 GB vanilla, 8 GB plugins or light mods, 16 GB heavyweights. On Astronomical you can ascend an orbit in one click and your world moves with you, so the cost of starting honest is nothing.