Project Zomboid server RAM: how much do you need?
Here it is distance between players that costs memory, not the number of players. Zomboid is the one game on this site where four people can be more expensive to host than twelve.
Recommendation
You need a server with at least
8GB
- Engine / Base OS:
- 4 GB
- Player Overhead:
- +2.4 GB
- Estimated Raw Usage:
- 6.4 GB
- Suggested cores:
- 4
- Disk to allow:
- 15 GB+
Cost scales with how many separate map regions are loaded, so spread-out players hurt more than crowded ones.
View 8GB PlansAdvertisement
What uses the memory in Project Zomboid
Cells of the map are streamed in around every player and held for as long as someone is close. Put four survivors in four towns and Knox County is loaded in four separate places; put twelve in one base and it is loaded once. Each zombie, each item on the floor and each piece of furniture someone built inside a loaded cell is tracked on its own.
Project Zomboid server RAM by player count
The calculator above, run for 3 common sizes. Each figure is rounded up to a plan size people actually sell.
| Players | Vanilla map | Heavy Map Mods / Vehicles |
|---|---|---|
| 16 | 8 GB | 12 GB |
| 32 | 12 GB | 16 GB |
| 64 | 16 GB | 24 GB |
Advertisement
Where people get it wrong
Going by slots alone. On a roleplay server where groups set up far from each other, size as if you had several times the players — and remember that big map mods and vehicle packs raise the baseline before the first connection.
Giving the server its memory
Zomboid runs on Java, and the most memory it may use is the -Xmx value in its launch configuration. Depending on the build, that line lives in the server's start script (StartServer64.bat on Windows, start-server.sh on Linux) or in ProjectZomboid64.json next to it, so check both. Set it to the figure above rather than trusting the default, and leave a gigabyte or two of the machine's memory outside it for the operating system.
Settings that change the load
PauseEmpty, on by default, freezes the world when nobody is connected, which saves CPU and keeps time from passing in an empty server. SaveWorldEveryMinutes decides how often the world is written; at its default of 0 the server only saves when it shuts down. The save itself, in Zomboid/Saves/Multiplayer/ under the server's name, is many small files covering every explored cell, so disk use grows with exploration in the same way memory does.