How to Allocate More RAM to Minecraft

Learning how to allocate more RAM to Minecraft takes about five minutes, and the setting lives in your launcher, not in the game. This guide covers the official launcher, CurseForge, Prism and Modrinth, then the part most guides skip: how much to actually give it, and why more is not better.

Before you start

Quick answer

The control has a different name in every launcher, but sets the same number underneath.

• Official launcher. Installations, edit the profile, More Options, then change -Xmx2G in the JVM Arguments box.
• CurseForge. Settings, Minecraft, then the Allocated Memory slider, or per pack under Profile Options.
• Prism Launcher. Settings, Java, then Maximum memory allocation, in MB.
• Modrinth App. Default instance options, or Java and Memory on one instance.

For most players the answer is between 4 GB and 8 GB.

What the RAM setting does

Minecraft Java Edition runs inside the Java Virtual Machine, which reserves a pool of memory called the heap. Loaded chunks, entities and objects created by mods use this heap, while graphical assets can also require memory elsewhere in the system. Three things get called RAM, and mixing them up is where bad advice begins.

• System RAM is what is physically installed in your computer.
• Allocated RAM is the ceiling you set for the heap, and the number you change.
• Used RAM is how much of that ceiling the game is touching now, usually far less.

The ceiling comes from a startup argument called -Xmx. Writing -Xmx6G means never let the heap pass 6 GB, and a slider writes the same thing in megabytes. Raising it hands nothing over; it only lets the game grow if a world needs the room.

How much RAM do you need?

Allocation follows the workload, not the size of the machine. Treat these as starting points.

• Vanilla: 2 GB to 4 GB is usually enough. Giving it more generally does not provide a meaningful benefit.
• A few mods: 4 GB to 6 GB.
• Medium modpacks: 6 GB to 8 GB.
• Large modpacks: 8 GB to 12 GB.

Then check that against the machine. A useful starting point is to keep Minecraft's allocation around half of your system RAM while leaving enough memory for the operating system and other applications. For example, that could mean around 3 GB to 4 GB on an 8 GB computer, 6 GB to 8 GB on a 16 GB computer, or 8 GB to 12 GB on a 32 GB computer. Where a modpack states its own recommendation, use that instead.

Setting it in your launcher

Official Minecraft Launcher

CurseForge

Open Settings, choose Minecraft, and drag the Allocated Memory slider in the Java block. It saves as you move it and applies to every pack not told otherwise. For a heavy pack, set it on the pack instead: My Modpacks, the three dot menu, Profile Options, then custom allocation.

Prism Launcher

Settings, the Java tab, then Maximum memory allocation, in megabytes: 4096 for 4 GB, 8192 for 8 GB. Instances can override this, which is the tidy way to give one demanding pack more without raising it everywhere.

Modrinth App

For a default new instances inherit, enter the figure under Default instance options. To change one instance only, open it, go to Java and Memory and switch on custom memory allocation.

Check that it worked

Load a world and press F3, or Fn and F3 on some laptops. The debug screen shows Mem: 3500/8192 MB top right: the second figure is your allocation, so that is an 8 GB ceiling with 3.5 GB in use. Task Manager reports more, because it counts memory outside the heap.

Does more RAM boost FPS?

No, not directly, and this is the most common misunderstanding about the setting. Frame rate comes from your graphics card, processor, render distance, video settings and whether shaders are running. None of those is a memory problem, so at 40 frames per second with memory to spare, raising it changes nothing.

What it does fix is running out: out of memory crashes, stalls while a large pack loads chunks, and the stutter that appears once the heap is nearly full. An oversized heap can also mean longer garbage-collection pauses, so allocating far more RAM than Minecraft needs can introduce stuttering instead of improving performance.

Still crashing? Common problems

Modded and modpack RAM

Mods raise memory use because they add things to keep track of: new blocks, items, entities and dimensions, extra world generation, machines that run constantly, and client-side additions such as minimaps. Higher render distances load more chunks, and high-resolution texture packs add to the total.

None of that scales cleanly with mod count, so one hundred mods needing exactly eight gigabytes is not a real rule: a tightly built pack of 200 can be lighter than a sprawling one of 80. Where a pack publishes a figure, as most on the modpacks pages do, that figure wins.

Client RAM and server RAM

These are separate settings on separate machines and do not need to match. Client RAM is the heap on your own computer, which is everything above. Server RAM belongs to whatever hosts the world and affects tick rate and player capacity, so your own allocation will not fix a session where the server is struggling.

Server memory works the same way underneath, through -Xmx in a start script or a hosting panel slider, with -Xms commonly matched to it for steadier ticks.

FAQ