Should Xms and Xmx be equal? What values?
Setting your minimum RAM (Xms) equal to your maximum (Xmx) is a common, safe choice for Minecraft servers. It's not required, but it avoids some overhead and matches how most server operators run things.
Why Xms = Xmx works well
When Xms equals Xmx, the JVM allocates the full heap up front and never has to resize it during play. That's standard practice for Minecraft servers and keeps memory behavior predictable. The one hard rule: Xms must never exceed Xmx, or the server crashes instantly.
How to set the values
- Open the Startup tab.
- Set Minimum RAM (Xms) at or equal to Xmx.
- Leave the recommended RAM Buffer in place as headroom — the buffer lowers usable Xmx to prevent OutOfMemory.
Warning: Never set the minimum above the maximum. Xms higher than Xmx is the classic cause of an instant crash on startup.
Frequently asked questions
Is it required to set Xms = Xmx? No, but it's a safe and common choice that avoids heap resizing. Just keep Xms at or below Xmx.
Where do I set these? In the Startup tab, via the Minimum RAM and RAM Buffer variables. The buffer provides the headroom that keeps the JVM from running out.