Every Minecraft launcher lets you raise how much memory the game can use, from a slider in the Modrinth App to a -Xmx value tucked into More Options in the official launcher. Setting it takes under a minute in any of them. What takes longer, and matters more, is figuring out whether a RAM shortage is actually your problem before you touch the number.
More RAM is not automatically the fix
RAM also does not raise your frame rate. Frame rate comes from your GPU and CPU, how fast the graphics card renders each frame and how fast the processor keeps up with world generation and entity ticking. A RAM shortage shows up as stutters, freezes, and out-of-memory crashes, not a low FPS number that holds steady. If low FPS is the actual complaint and nothing is freezing or crashing, more RAM almost never moves it, and the last section of this guide covers what does.
Check how much RAM your computer actually has
Know the ceiling before you set a number. Leave enough for the operating system itself, plus your browser, Discord, and anything else open, or you trade one stutter for another.
On Windows
Open Settings, then System, then About. Installed RAM is listed under Device specifications. Task Manager, opened with Ctrl+Shift+Esc, shows the same total on its Performance tab under Memory, along with how much is currently in use.
On macOS
Click the Apple menu in the top-left corner and choose About This Mac. The Overview tab lists total Memory in gigabytes.
What the -Xmx argument means
-Xmx is the Java argument that sets the maximum heap size, the most memory Minecraft's process is allowed to claim. -Xmx4G allows up to 4 gigabytes, and -Xmx4096M sets the identical limit in megabytes, since 1024M equals 1G. A matching -Xms argument sets the starting heap size rather than the ceiling. Most players can leave it alone, or set it equal to -Xmx so the JVM does not resize the heap mid-session. Every launcher below either exposes this as a slider measured in gigabytes or lets you edit the raw argument directly, and they set the same value either way.
How much RAM to allocate by use case
There is no single correct number. What a setup actually needs depends on the mod count and what those mods do, not how heavy the pack feels.
- Vanilla, or vanilla plus a handful of small mods: 2 to 4 GB. Vanilla rarely needs more, and giving it more buys nothing.
- Light mod list, roughly 20 to 50 mods, mostly quality-of-life and optimization: 4 to 6 GB.
- Heavy modpack, 100 or more mods, tech or magic packs with world generation additions: 6 to 8 GB, occasionally more for the largest kitchen-sink packs.
- Shaders on top of a mod list: add 1 to 2 GB to whatever the mod list alone needs. Shaders mainly load the GPU, not system RAM, so the bigger lever for shader performance is the preset and resolution scale in the shader pack's own settings, not the memory slider.
Set RAM in your launcher
The setting lives in a different place in every launcher. These steps match each app's current interface.
Official Minecraft Launcher
- 1.Open the Minecraft Launcher and click Installations at the top.
- 2.Find the installation you play, for example Latest release, open its menu, and choose Edit.
- 3.Click More Options to reveal the advanced settings.
- 4.In the JVM Arguments field, find the existing -Xmx value, such as -Xmx2G, and change just that number. Leave the rest of the line alone; it includes garbage-collection flags the launcher set for a reason.
- 5.Save the installation, then launch normally.
Modrinth App
- 1.Open the Modrinth App and click the gear icon to open Settings.
- 2.Go to the Default instance options tab and drag the Memory allocated slider to your target amount. That sets the default for every instance.
- 3.To override a single instance instead, open that instance's own settings, turn on custom memory allocation, and drag its slider separately.
CurseForge app
- 1.Click the gear icon in the lower-left corner to open Settings, select Minecraft under Game Specific Settings, and move the Allocated Memory slider under Java Settings. That sets the default for new profiles.
- 2.For one modpack only, go to My Modpacks, open that profile's menu, choose Profile Options, turn off Use System Memory Settings, and adjust the slider there instead.
Prism Launcher
- 1.Open Prism Launcher, choose Settings, then the Java tab. Its Memory section holds Minimum and Maximum memory allocation fields; raise the maximum value and confirm. This sets the global default.
- 2.For a single instance, select it, choose Edit Instance, open its Settings tab, then its own Java tab, tick the Memory box, and set that instance's maximum value separately.
MultiMC
- 1.Right-click the instance and choose Edit Instance.
- 2.Open Settings, then the Java tab, and tick the Memory checkbox.
- 3.Set Minimum and Maximum memory allocation to matching values. Keeping them equal avoids the JVM resizing the heap mid-session.
Allocating RAM in the official launcher and CurseForge app
When RAM isn't the bottleneck
If you raised the ceiling and nothing changed, or the real complaint was low FPS rather than crashes and freezes, RAM was never the problem. Frame rate is a rendering and simulation question, and that is a job for optimization mods, not memory.
Sodium replaces the game's rendering engine and is the single biggest FPS gain available on Fabric or NeoForge. Lithium pairs with it on the simulation side, covering mob AI, chunk loading, and redstone. FerriteCore is worth adding too, though it targets lower memory use rather than higher FPS, so do not expect it to move your frame counter on its own. ModernFix targets game startup and world loading times specifically, and ImmediatelyFast speeds up UI and text rendering that can bottleneck on weaker CPUs. For a ready-made bundle instead of picking mods one at a time, Fabulously Optimized packages most of these together with sane defaults.
If you are not sure where the bottleneck actually is, install spark and run a profile while the stutter happens. It points at the specific mod, tick phase, or render step spending the time, instead of leaving you to guess.
Frequently asked questions
How much RAM should I give Minecraft?
2 to 4 GB covers vanilla and light mod lists, 4 to 6 GB covers a moderate mod list, and 6 to 8 GB covers most heavy modpacks. Go by what your mod list or pack actually needs rather than assuming more is always better, and stay under roughly half your total system RAM so the rest of your machine keeps working.
What does -Xmx mean in Minecraft?
-Xmx is the Java argument that sets the maximum heap size, the most memory Minecraft's process can use. -Xmx6G allows up to 6 gigabytes, and the number can also be written in megabytes, where 1024M equals 1G. It sets a ceiling, not a guarantee that Minecraft will use all of it.
Does more RAM increase FPS in Minecraft?
No, not directly. RAM prevents out-of-memory crashes and the stutters that come from the game running out of space to work in. Frame rate depends on your GPU and CPU, so a low FPS number with nothing crashing or freezing points to a rendering or simulation problem, not a memory one.
How do I increase FPS in Minecraft?
Install a rendering optimization mod such as Sodium if your loader supports it; it typically delivers a bigger FPS gain than any other single change. Lower your render distance and turn off smooth lighting or fancy graphics if you are still short after that, and confirm your GPU driver is current.
How do I make Minecraft run faster?
Combine a few things rather than relying on one setting: an optimization mod list like Sodium and Lithium, a RAM allocation that matches what your mod list actually needs, a lower render distance, and closing background apps competing for the same CPU and GPU. None of these alone fixes every case, but stacked together they cover most performance complaints.
Can allocating too much RAM cause problems?
Yes. A very large heap gives Java's garbage collector more to scan when it runs, which can produce longer pauses instead of smoother play. Allocating more than your computer physically has forces the operating system to swap to disk, which is far more disruptive than the shortage you were trying to fix.
