A smooth Project Zomboid server comes down to three things: enough RAM, a sensible zombie population, and a restart once a day. Start with 8 GB for a small group, and go to 10 GB or more once you add mods. Build 42 needs about a third more memory than Build 41.
How much RAM you need
RAM is the server’s memory. Project Zomboid keeps the map around every player, every zombie near them and every mod’s data in it.
| Players | No mods | With mods |
|---|---|---|
| 1 to 6 | 8 GB | 10 GB |
| 6 to 12 | 10 GB | 12 GB |
| 12 to 20 | 12 GB | 16 GB |
| 20 or more | 16 GB | 16 GB or more |
These are starting points for Build 42. A Build 41 server can often use one size smaller. Big map mods and long mod lists push you up a size. You can change plans any time without losing your world.
The memory setting
Project Zomboid runs on Java, and Java needs to be told how much memory it may use (the -Xmx setting). We set it from your plan, leaving a little room for the system, and change it when you change plans. You don’t need to edit anything.
If you run a server yourself, the setting is in ProjectZomboid64.json in the server folder on Linux, or in StartServer64.bat on Windows.
Settings that cost the most
| Setting | Where | Why it matters | Try |
|---|---|---|---|
| Zombie population | Zombies and PopulationMultiplier in wilderack_SandboxVars.lua |
More zombies means more to track and send to players | Normal (4) or low (5) for big groups |
| Max players | MaxPlayers in wilderack.ini |
Each player loads their own piece of the map | Keep it near your real group size. The game warns that above 32 can lag |
| Mods | Mods and WorkshopItems |
Each mod adds memory and loading time | Remove mods nobody uses |
| Map mods | Map |
Extra towns make the world bigger to load and save | Add one at a time and watch RAM |
| Pause when empty | PauseEmpty in wilderack.ini |
Stops the world when nobody’s on | Leave it on (true) |
Players spread far apart cost more than the same players in one base. Long drives load new map pieces quickly, so driving around is when lag shows first.
Restart once a day
Java servers slowly fill their memory the longer they run. A daily restart clears it and also picks up mod updates from the Workshop.
- Open Schedules.
- Add the preset Daily restart with warnings. It warns players 5 minutes and 1 minute before.
- Pick a quiet time, like 5:00 in the morning for your group.
If the server is asleep at that time, the restart is skipped, since nobody’s playing.
World size
The save grows as players explore. A world that’s been played for months can take up a lot of disk space and take longer to back up. That’s normal. If your group wants a fresh start, make a new save in Games instead of deleting the old one. You can switch back any time.
Pick the right region
Choose EU or US East, whichever is closest to most of your players. Low ping matters in Project Zomboid, where a late hit can mean a bite. You pick the region when you create the server. Ask support at support@wilderack.com if your group moves.
Read the graphs on Overview
Overview shows CPU, RAM, players and network over 24 hours and 7 days.
- RAM close to your plan’s limit most of the time: go up a plan, or remove mods. When Java runs out of memory, the server crashes.
- CPU spikes when players spread out or drive: lower the zombie population or ask the group to stay closer together.
- RAM climbs a little every day: normal for Java. A daily restart resets it.
- Network spikes when someone joins: that’s the map and mods loading for them. It settles once they’re in.
If the server crashes, Console shows a helper card with a plain-words hint. See common errors for more.
Questions
How much RAM does a Project Zomboid server need?
About 8 GB for a few friends with no mods, 10 GB with mods or up to 10 players, and 12 to 16 GB for bigger groups or long mod lists. Build 42 needs about a third more than Build 41.
Why does my Project Zomboid server lag when we drive?
Driving loads new parts of the map quickly, and every player in a different place makes the server load a separate area. Fewer zombies, fewer players spread far apart, and enough RAM all help.
Do I need to set -Xmx on my Project Zomboid server?
Not on Wilderack. We set the Java memory limit from your plan, and it changes when you change plans. If you host the server yourself, it's in ProjectZomboid64.json on Linux or StartServer64.bat on Windows.
Sources we checked
- Server settingsPZwiki (official Project Zomboid wiki)
- Tech support (server memory)PZwiki (official Project Zomboid wiki)
- Build 42.21 stable releasedThe Indie Stone
