How to Allocate More RAM to Minecraft (Launcher, CurseForge, Servers)

Minecraft Java Edition only uses as much memory as you let it. The official launcher gives it 2 GB by default, which is fine for vanilla but too little for big modpacks, high render distances or shaders. When Minecraft runs out of memory you get stutters, long freezes and sometimes an out of memory crash. This guide shows how to allocate more RAM to Minecraft in every popular launcher and on a server, how much RAM to give, and when more RAM will not help.

Quick answer: allocate more RAM in the Minecraft Launcher

1. Open the Minecraft Launcher and select Minecraft: Java Edition.
2. Click the Installations tab.
3. Hover over the installation you use, click the three dots, then Edit.
4. Click More Options.
5. In JVM Arguments, find -Xmx2G at the start of the line.
6. Change the number, for example to -Xmx4G for 4 GB or -Xmx6G for 6 GB.
7. Click Save and launch the game.

Change only the number after -Xmx and keep the capital G. Do not delete the rest of the arguments. Bedrock Edition does not have this setting, because it manages memory on its own.

How much RAM should you allocate to Minecraft?

As a rule, never give Minecraft more than half of your computer’s total RAM. Windows, your browser, Discord and the graphics driver need memory too. On an 8 GB computer, 4 GB is the sensible maximum. On 16 GB, 6 to 8 GB is plenty for almost anything.

Why more RAM is not always better

Java cleans up unused memory in a process called garbage collection. If you allocate far more memory than Minecraft needs, each cleanup has more to scan and can cause longer pauses, which feel like lag spikes. A vanilla game with 16 GB allocated often runs worse than with 4 GB. Give Minecraft enough, not everything.

How to check how much RAM Minecraft is using

Press F3 in game (Fn plus F3 on some laptops). The top right corner shows Mem, the percentage of allocated memory in use, and Allocated. If Mem keeps climbing to 90 percent or more and the game stutters, add more RAM. If it stays below 60 percent, more RAM will not help, and lag is coming from something else.

Allocate RAM in other launchers

CurseForge app

1. Open CurseForge and click the gear icon for settings.
2. Go to Minecraft under Game Specific.
3. Under Java Settings, drag the Allocated Memory slider.
4. Close settings and launch your modpack.

You can also set memory per profile: right-click a modpack, choose Profile Options, and turn off Use System Memory Settings.

Modrinth App

Open Settings, then Java and memory, and set the maximum memory. Individual instances can override it in their own settings under Java and memory.

Prism Launcher and MultiMC

Open Settings, then Java, and set Maximum memory allocation. For one instance only, edit the instance, open Settings, tick Memory and set the values there.

ATLauncher and Technic

Both have a memory or Java settings page with a maximum memory field or slider. Technic also requires a 64-bit Java to use more than about 1 GB.

Allocate more RAM to a Minecraft server

A Java server’s memory is set in the command that starts it. Edit your start script, often called start.bat on Windows or start.sh on Linux and macOS:

java -Xms2G -Xmx4G -jar server.jar nogui

-Xmx is the maximum and -Xms is the starting amount. Raise -Xmx to give the server more RAM. On a hosting company’s server, memory is set by your plan, so upgrade the plan instead. See how to make a Minecraft server.

Troubleshooting

• Game does not start after the change: you probably typed the argument wrong. Make sure it is -Xmx4G with no spaces, or reset the JVM arguments to default.
• Could not reserve enough space for object heap: you are using 32-bit Java, or asked for more RAM than is free. The official launcher bundles 64-bit Java, so use the bundled runtime.
• Still laggy: RAM may not be the problem. Lower render distance, install Sodium, update graphics drivers, or check for a heavy mod. See why is Minecraft so laggy.
• Java version: since Java Edition 26.1, Minecraft needs Java 25. The launcher includes it, so leave the Java executable setting on default unless you know you need another.

Other ways to make Minecraft run better

• Install Sodium or use a performance modpack such as Fabulously Optimized.
• Lower render distance and simulation distance. See how to change render distance.
• Close browser tabs and background apps before playing.
• On laptops, plug in the charger and set Windows to high performance.

Signs that Minecraft needs more RAM

Before you change anything, it helps to know whether memory is really the problem. Minecraft that is short of memory shows a clear pattern: the game runs smoothly for a while, then freezes for a second or two, then runs smoothly again. The F3 screen’s memory value climbs close to 100 percent and suddenly drops back down after each freeze. Loading a big modpack may also stall on the loading screen or crash with an error that mentions an out of memory exception or a Java heap space problem. If you see low frame rates without freezes, the cause is usually your graphics card or settings, not memory, and adding RAM will not fix it.

Recommended settings by computer

• 4 GB computer: leave Minecraft at 2 GB, play vanilla with Sodium and a render distance of 8.
• 8 GB computer: allocate 3 to 4 GB. Light shaders and small modpacks work well.
• 16 GB computer: allocate 6 to 8 GB. Almost every modpack and shader runs comfortably.
• 32 GB or more: 8 to 12 GB covers even the largest modpacks. Going higher rarely helps.

If you also run a local server on the same computer, add the server’s memory to Minecraft’s and keep the total under half of your system RAM.

FAQ

How do I give Minecraft more RAM?

In the Minecraft Launcher, edit your installation, open More Options and change -Xmx2G in JVM Arguments to a higher value such as -Xmx4G.

How much RAM should Minecraft have?

2 to 4 GB for vanilla, 4 to 6 GB for shaders or small modpacks, and 6 to 10 GB for large modpacks. Never use more than half your system RAM.

Can you allocate more RAM to Minecraft Bedrock?

No. Bedrock Edition manages memory automatically and has no RAM setting.

Does more RAM increase FPS?

Only if Minecraft was running out of memory. Too much RAM can cause lag spikes from longer garbage collection.

How do I check Minecraft memory usage?

Press F3 and look at the Mem line in the top right corner.

Checked by the Game Respawned editorial team against the current Java and Bedrock versions. Spotted something out of date? Tell us.