Set RAM and Java Flags on Your Minecraft Server

The RAM of your Minecraft server comes from your plan, so you raise it by upgrading the plan. What you can tune yourself is how Java uses that memory: open Settings > General > Startup, limit the Java memory (heap) if you need to, choose a profile in Java performance and restart. By default the panel already makes Java use little memory while the server is quiet and grow only when there is load.

How much RAM does your server need?

There is no single number, because it depends on what the server runs. As a guide:

• A small survival server with a few friends and no plugins needs little.
• Plugins, more players, bigger view distance and bigger worlds all add up.
• Modpacks need far more than plain Paper or Vanilla.

The panel estimates it for you. Go to Console > Performance and find the Memory (RAM) card:

• Your plan shows your RAM, In use now shows what the server is using, and What it needs is an estimate based on your plugins or mods, the world size and the players you usually have.
• The verdict is one of Needs more, Fine or Plenty left, with a Recommended amount.
• If it says Needs more, click Upgrade plan. See how to upgrade your game server plan.

If you are installing a modpack, the installer also compares the pack's recommended RAM (an estimate for 10 players) against your plan before you confirm.

How your server uses memory: Automatic and elastic memory

The RAM of your plan is what the server has in total, but Java does not use all of it for the same thing: it splits memory in two parts.

• The heap is the memory Java uses to run the game itself (world, entities, plugins and mods).
• The rest, outside the heap, is needed by threads, the Java engine, mods with their own memory and network connections.

If the heap takes the whole plan, there is no room left for the second part and the system can shut the server down without Java saying anything. That is why the panel always leaves a margin.

In Automatic, which is the default, the panel uses elastic memory:

• Java starts with little memory (128 MB) and uses little while the server is quiet.
• When there is load (players, chunks, mods) it grows by itself, up to a safe maximum: your plan minus the margin for the part outside the heap.
• When the load drops, Java gives part of the memory back to the system. This last part needs Java 17 or newer; with an older version Java grows the same but does not give it back.

This helps a lightly used server take up little, but there is no guarantee that Java gives all the memory back: Minecraft reserves a lot when it loads the world, chunks and mods, so what you save depends on your server. If your provider turns elastic memory off, Automatic goes back to how it always was: Java can grow up to the whole plan.

Limit the Java memory

If you want to set the maximum Java can use yourself, for example because a heavy modpack freezes for a moment every so often, do this:

1. Sign in to the SolumeCore panel, open your server, go to Settings and choose the General group.
2. Open Startup and scroll down to the Java memory (heap) card.
3. Choose Limit it. Instead of Automatic you will see Maximum for Java, with the value and the percentage of your plan it represents.
4. Drag the slider or use the buttons: Use the recommended (a midpoint of what usually works), Minimum or Safe maximum. The green band under the bar marks the recommended range.
5. Click Save changes. The panel confirms "Startup saved".
6. Restart the server. The limit applies the next time it starts.

To go back, choose Automatic and save.

How much to choose

The panel only lets you choose within a range that depends on your plan: the minimum is the greater of 512 MB and 25% of the plan, and the safe maximum is the plan minus a margin for the part outside the heap (at least 10% of the plan, and more on small plans and on 6 to 12 GB plans). Values go in steps of 128 MB. This table shows the real range for each plan size:

As a rule, use the recommended value or the Use the recommended button. From 32 GB the recommended range stops growing on purpose: more heap does not give more players and does give longer pauses.

What the warnings mean

If the value you pick deserves a warning, it appears under the bar. You can still save it.

• That's quite low for your plan. The heap is well below the recommended range: with many mods or players the server can run out of memory. Raise it to at least the recommended value.
• That's very close to the limit. Java also needs memory outside the heap. If the server shuts down on its own, lower the value.
• Above 32 GB Java loses compressed pointers. This is a Java optimization: past that size the extra memory adds little and pauses grow. This warning does not show with the Pausas mínimas (ZGC) profile, which does not use compressed pointers.

If your plan changes after you choose a value, the panel trims it to the new plan's range and tells you (for example, "You chose 24 GB, but your plan changed, so Java now uses 7 GB"). Your choice is kept, so if the plan grows again, what you chose comes back.

More RAM for Java is not more speed

Giving Java more memory than it needs does not speed anything up, and it can make things worse: a huge heap makes memory cleanups longer, and if no margin is left for what lives outside the heap the system can shut the server down. The memory you do not give to Java is not wasted: the system uses it to cache files, which helps the server.

When the option does not show or cannot be changed

• "This server doesn't support a memory limit from the panel." The server does not start with Java in the usual way (for example, it is not a Java server) or its start command has custom logic. Contact support if you need it.
• "A plan of X is too small to set a limit." With 1 GB or less Java already uses the little that is available and only Automatic exists.
• The card is greyed out. Your account may lack permission to edit startup, or the server is suspended or being installed.
• "Your provider manages this setting." The SolumeCore team has blocked the change, on every server or just on yours. You see the current value but cannot change it. What you had already chosen is kept.

Why you cannot type the memory flags yourself

The start command of your server contains the memory settings, for example Java's maximum memory, and the panel fills them from your plan and from the Java memory (heap) you choose. The command is shown in read-only mode, because one wrong character stops the server from starting. You change how it starts with the Java memory, a profile and the variables, never by editing the command.

Choose a Java flags profile

1. Sign in to the SolumeCore panel, open your server, go to Settings and choose the General group.
2. Open Startup. At the top you see the Start command with the variables highlighted.
3. In Java performance, pick a profile. The current one shows Current, and the best one for your memory shows Recommended.
4. Click Save changes. The panel confirms "Startup saved".
5. Restart the server to apply it.

The profiles are:

The panel shows these names as written above. If your memory does not suit a profile, a warning appears under it, and you can still choose it.

Profiles do not apply to every server

Profiles change the Java part of the command, so they only apply when the server starts through Java in the usual way. If your server does not (for example, a non-Java server), the panel shows a note and the profile cards are disabled. For Forge and NeoForge, the panel writes the flags and the memory to the user_jvm_args.txt file for you. If you edit that file by hand, the next profile or memory change overwrites it.

Custom flags

The profile list does not take free text. If you need a specific set of flags that none of the profiles covers, open a ticket from the panel and tell us which ones, and our support team will take a look. A start command written by our staff shows as A medida, and the panel will not change it.

Check the result

1. After the restart, watch the server for a while with players online.
2. Use tps in the console on Paper and similar software to see the ticks per second. 20 is perfect.
3. If lag remains, the cause is often not Java but plugins, chunks or entities. Read how to fix lag and low TPS.

Troubleshooting

• The server does not start after changing the profile. Go back to Normal and restart. If you chose Pausas mínimas (ZGC), make sure your Java is 21 or newer in Java version.
• The server shuts down on its own, with no error. You may have left the Java memory (heap) limit too close to the cap, leaving no memory for what lives outside the heap. Lower it, or go back to Automatic, and restart.
• The profile cards are greyed out. Your account may lack permission to edit startup, the server may be suspended, or the server does not start with Java in the usual way.
• I changed it but nothing improved. Flags help with pauses, not with a server that lacks RAM or CPU. Check the Memory (RAM) verdict.
• Memory usage goes up and down. That is expected with elastic memory: it grows with load and drops when the server calms down. If it never drops, make sure your Java is 17 or newer.
• Memory usage jumps when the world loads. Minecraft reserves a lot while it loads chunks and mods. That is normal and does not mean anything is failing.

FAQ

How much RAM do I need for a Minecraft server?

It depends on players, plugins, mods and world size. Open Console > Performance and read the Memory (RAM) card for an estimate based on your own server.

What are Aikar's flags?

A set of Java settings published by a well-known Paper developer and used across the community. They make Java clean up memory in short, frequent steps, so players notice fewer freezes. In the panel they are the Optimizado (Aikar) profile.

Can I set -Xmx and -Xms myself?

You can choose Java's maximum memory (-Xmx) in Settings > General > Startup > Java memory (heap). You do not type the command by hand. The initial memory (-Xms) is managed by the panel.

Does giving Java more memory make the server faster?

No. A heap larger than needed makes memory cleanups longer and leaves less margin for the rest of the server. What usually works is in the table above. If the server is tight, the fix is a plan with more RAM.

Do more flags make the server faster?

No. Use one profile that matches your memory. Mixing flags by hand tends to make things worse.

Related articles

• Change the Java version of your Minecraft server
• Fix lag and low TPS on your Minecraft server
• Upgrade your game server plan
• Edit server.properties in Minecraft

Need more memory for a growing community? Compare our Minecraft server plans.