How to Allocate More RAM to Minecraft: the 2026 Guide

To allocate more RAM to Minecraft: open your launcher’s settings and raise the memory limit. Give vanilla 2 GB, a lightly modded game 4-6 GB, and a big modpack 8 GB. In the official launcher, go to Installations, click the three dots on your profile, choose Edit, open More Options, and change -Xmx2G to -Xmx4G in the JVM Arguments box. More is not always better: past 8 GB you get longer stutter pauses, and you must leave RAM for the operating system.

How much RAM should you give Minecraft?

Minecraft runs on Java, and the -Xmx value sets the maximum heap the game may use. The official launcher ships with 2 GB, which is fine for vanilla but not for a pack with 150 mods. This table covers the sane range:

What you play	RAM to allocate	The -Xmx value
Vanilla, or vanilla with light shaders	2 GB	-Xmx2G
Lightly modded (Fabric + Sodium, 20-50 mods)	4 GB	-Xmx4G
Medium modpacks (100-200 mods)	6 GB	-Xmx6G
Big kitchen-sink packs (300+ mods)	8 GB	-Xmx8G

Two facts keep people from overshooting. First, a huge heap makes Java’s garbage collector pause longer when it cleans up, so a client set to 16 GB often stutters more than the same client at 8 GB. Second, Windows or macOS needs its own share: leave at least 2-4 GB for the system, your browser, and Discord, or the whole machine starts paging to disk and everything slows down. If you want actual frame-rate gains rather than just headroom, our 8 performance mods that boost FPS do more for smoothness than any RAM slider.

A quick reality check beats guessing: press F3 in game and watch the Mem line in the top-right of the debug screen. If it sits around 40% of your allocation and never climbs, you gave the game more than it needs and can dial down a step. If it pins at 95-100% and the game stutters or crashes, raise the limit one step. Judge by the meter, not by a feeling.

Check how much RAM your computer has

Never allocate more than your machine owns. On Windows, open Task Manager (Ctrl+Shift+Esc), go to the Performance tab, and click Memory: the top-right number is your total RAM. On macOS, click the Apple menu and choose About This Mac: the memory line shows the total. A machine with 8 GB total should give Minecraft no more than 4 GB. A machine with 16 GB can comfortably give 6-8 GB.

Official Minecraft launcher

This is the launcher most players have. The setting hides behind a few clicks:

1. Open the launcher and click the Installations tab at the top.
2. Find the installation (profile) you play on. Hover over it and click the three dots on the right.
3. Choose Edit. A window opens with the profile settings.
4. Click More Options near the bottom to reveal the JVM arguments.
5. In the JVM Arguments box, find -Xmx2G at the start of the line and change it to your target, for example -Xmx4G or -Xmx6G. Change only that part; leave the rest of the line alone.
6. Click Save, then launch the game. The new limit applies from this launch on.

If you broke the line by accident, the default full string is -Xmx2G -XX:+UnlockExperimentalVMOptions -XX:+UseG1GC -XX:G1NewSizePercent=20 -XX:G1ReservePercent=20 -XX:MaxGCPauseMillis=50 -XX:G1HeapRegionSize=32M. Paste it back and change only the 2G.

CurseForge app

CurseForge uses a slider instead of a text box, which is harder to get wrong:

1. Open the CurseForge app and click the gear icon (Settings) in the bottom-left.
2. Choose Minecraft from the left sidebar.
3. Find the Allocated Memory slider under Java settings.
4. Drag it to your target (4096 MB for 4 GB, 6144 MB for 6 GB). The app shows the megabyte value as you drag.
5. Close settings. The change applies the next time you launch a modpack.

Note that this slider is global: it applies to every modpack you launch from the app. If one pack needs 8 GB and another runs fine on 4 GB, set the slider for the hungriest pack.

Prism Launcher

1. Open Prism Launcher and click Settings (top-right).
2. Go to the Java tab on the left.
3. Under Memory, set the minimum and maximum. A good pair is 1024 MB minimum and 4096-6144 MB maximum for a modded instance.
4. Click Close. Done; no restart of the launcher needed.

Prism also lets you set memory per instance: right-click an instance, choose Edit, go to Settings there, and tick the override. That is the cleaner option if your instances have very different appetites.

Modrinth app

1. Open the Modrinth app and click the instance you want to change.
2. Click the settings/gear for that instance.
3. Open the Java section.
4. Adjust the memory sliders to your target and save.

Like Prism, the Modrinth app keeps this per instance, so your 300-mod pack and your vanilla-plus-Sodium instance can each have their own limit. If you followed our Fabric and Sodium install guide, 4 GB on that instance is plenty.

Mistakes that waste RAM or break the game

Allocating 16 GB on an 8 GB machine. The game cannot reserve memory the computer does not have. You get “Could not reserve enough space for object heap” and the game refuses to start. Check your total first, as described above.

Setting the client but forgetting the server. If you run a modded server for friends, the server needs its own RAM setting (user_jvm_args.txt on a NeoForge server, or the -Xmx flag in the start command). A 6 GB client talking to a 2 GB server still lags when the server chokes.

The 32-bit Java trap. Ancient history for most players, but worth one line: 32-bit Java cannot address more than about 1.5 GB no matter what -Xmx says. Every current launcher installs 64-bit Java by default, so you only hit this with a manual Java install from years ago.

What about Bedrock, console, and mobile?

Nothing to do here. Bedrock Edition (phones, consoles, the Windows Bedrock app) manages its own memory; there is no JVM arguments box, no slider, no setting to change. If Bedrock runs badly, the fix is render distance and graphics settings, not RAM allocation. This whole guide is Java Edition only.

Troubleshooting

The launcher resets my JVM argument after an update

Launcher updates occasionally reset edited profiles. Reopen Installations, check the profile’s More Options, and re-enter your -Xmx value. If it keeps happening, duplicate the profile and edit the copy.

“Could not reserve enough space for object heap”

You asked for more RAM than the machine has free. Other programs eat into it too: close the browser with 40 tabs, then lower -Xmx until the game starts. On an 8 GB machine, -Xmx4G is the ceiling.

Stuttering got worse after I increased RAM

Classic overshoot. Drop the allocation back down: if 12 GB stutters, try 8 GB, then 6 GB. Longer garbage-collection pauses on a huge heap feel exactly like lag spikes. Find the smallest value where the game no longer throws out-of-memory errors.

The game will not start after I edited the JVM arguments

There is a typo in the arguments line. Restore the default string from the official-launcher section above and change only the -Xmx2G part. One misplaced character in a -XX: flag stops the JVM from starting at all.

Only change settings inside your launcher. You do not need any “RAM booster”, “game optimizer”, or “FPS unlocker” download to allocate memory; the setting is built into every launcher above. Third-party “booster” tools are a well-known source of adware and fake system cleaners. If a site tells you to download something to “unlock” more RAM for Minecraft, close the tab. When the game itself crashes after adding mods, work through our mod crash troubleshooting guide instead of guessing.

FAQ

Does more RAM increase FPS?

Not directly. More RAM stops stuttering caused by garbage collection and prevents out-of-memory crashes, but your frame rate comes from the CPU, the GPU, and performance mods. If the game runs but feels slow, RAM is probably not the bottleneck.

How much RAM does the official launcher use by default?

2 GB (-Xmx2G). That is enough for vanilla and light modding, and it is why big modpacks crash on a fresh install until you raise it.

Can I allocate RAM on Bedrock, console, or mobile?

No. Those versions manage memory themselves and expose no setting for it. Lower the render distance and turn off fancy graphics instead.

I have 32 GB of RAM. Should I give Minecraft 24 GB?

No. Anything past 8 GB on a client buys you longer stutter pauses, not smoother play. The exception is a heavily modded dedicated server, which can genuinely use 10-12 GB for a huge pack with many players.

Do I need to restart the launcher after changing it?

You need to relaunch the game, not the launcher itself. The memory limit is read when the game starts, so quit to the launcher and press Play again.

What if my computer only has 8 GB total?

Give Minecraft 4 GB and keep the rest for Windows or macOS. Close heavy background apps before playing. A light Fabric + Sodium setup at 4 GB runs well on an 8 GB machine.