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Increase Server RAM

Project Zomboid Guide • Updated Mar 26, 2026

How to Increase Server RAM Allocation

If you are hosting a Project Zomboid Dedicated server locally through Steam CMD or the Steam Library, you will absolutely need to adjust the default RAM settings. By default, the memory allocation is set quite low (usually around 3GB). If you are running multiple large map mods or playing with a group, you must increase this limit to prevent severe lag and server crashes.

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Adjusting the Memory Limits

  1. In your Steam Library, right-click the Project Zomboid Dedicated Server tool, select Manage, and click Browse Local Files.
  2. In the newly opened folder, locate the file named ProjectZomboid64.json.
  3. Right-click the file and open it with a text editor like Notepad.
  4. Scroll down to the vmArgs section until you find the line containing:
    -Xmx3072m (This indicates a strict 3GB memory limit).
  5. To give your server more breathing room, you will replace that single line with two specific Java arguments mapping the minimum and maximum memory. Replace the line with: 
    -Xms2048m
-Xmx8192m
  6. Understanding the Values:
    • -Xms dictates the initial guaranteed memory (e.g., 2048m = 2GB). This ensures map mods stay loaded efficiently.
    • -Xmx dictates the absolute maximum memory the server is allowed to use (e.g., 8192m = 8GB).
  7. Crucial Warning: Never allocate more RAM to the server than your PC physically has. For system stability, always leave at least 4GB of RAM free for Windows and background apps. For example, if your computer has 16GB of total RAM, your absolute maximum -Xmx value should not exceed 12GB (-Xmx12288m).
  8. Once finished modifying the values, save the file and launch the server.
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