How to allocate more RAM to Minecraft and boost FPS

Minecraft Java Edition runs inside Java, and the launcher decides how much memory Java may use. Since 26.1 the default is 4 GB, which is enough for the vanilla game. More RAM helps with big modpacks and HD texture packs, but for FPS the video settings and a mod like Sodium matter far more.

• Windows: open the Task Manager (Ctrl + Shift + Esc), then Performance and Memory. The total is shown at the top right.
• macOS: Apple menu, About This Mac, line Memory.
• Linux: type free -h in a terminal and read the "total" column.

Note the number. Minecraft has to leave enough memory for the system, the graphics driver and the apps you keep open, such as a browser or Discord.

1. Open the Minecraft Launcher and select Minecraft: Java Edition.
2. Go to the Installations tab.
3. Hover over the installation you play, click the three dots and choose Edit.
4. Click More Options.
5. In JVM Arguments, change the number in -Xmx4G, for example -Xmx6G for 6 GB.
6. Click Save, then Play.

For 26.3, the default arguments are -Xms2G -Xmx4G -XX:+UseCompactObjectHeaders -XX:+AlwaysPreTouch -XX:+UseStringDeduplication -XX:+UseZGC. The last one selects the ZGC garbage collector on macOS, Linux and Windows 10 version 1803 or newer. Older Windows versions get the G1 collector instead.

• -Xmx is the maximum memory, -Xms the amount reserved at startup. Change only -Xmx and leave the other arguments as they are.
• Keep -Xms at or below -Xmx: Java refuses to start if the starting size is larger than the maximum.
• G means gigabytes. You can also write megabytes, for example -Xmx6144M.
• Before 26.1 the default was -Xmx2G. Installations of 1.21.11 and older still use it: raise it the same way if you play those versions.

The only official figure is Mojang's default: 4 GB, raised from 2 GB in 26.1 "to make the game run smoother and reduce stutters". The values below are common starting points, not rules. Adjust them with the F3 check in the next step.

Never give Minecraft more than about half of your PC's memory. With 8 GB in total, keep the default 4 GB. With 16 GB, 8 GB is a sensible ceiling.

More is not better. Java lets used memory pile up, then frees it in a pass called garbage collection, which can freeze the game for a moment. With the G1 collector, a larger heap means rarer but longer pauses. ZGC, the default on most computers since 26.1, keeps pauses short (Mojang switched to it for a more stable framerate), but it cannot help when the system itself runs out of memory: Windows or macOS then swaps to disk and the whole game stutters. Remember that the Java process uses more than the -Xmx value, because native memory comes on top.

Press F3 in game. The debug screen shows a memory block:

• Mem: the share of memory in use, then used and maximum memory in MB. The maximum is your -Xmx value.
• Allocation rate: how fast the game creates new data, in MB per second.
• Allocated: how much of the maximum Java has already taken from the system.

The Mem percentage rising and dropping is normal. If it keeps climbing close to 100% and the game freezes or crashes with an out of memory error, raise -Xmx by 1 or 2 GB. If it never goes much past half, extra RAM will not change anything. Press F3 + F6 to open Debug Options, where you can set the memory entry to Always so it stays on screen while you play.

Modpack launchers manage memory with their own setting, and Mojang warns that third-party launchers may not apply the 26.1 defaults. Change the value in the app, not in the Minecraft Launcher.

• CurseForge: click the gear at the bottom left, then Minecraft under Game Specific, and move the Allocated Memory slider in Java Settings. For a single modpack, open its profile, click the three dots next to Play, choose Profile Options, untick "Use System Memory Settings" and move that slider.
• Modrinth App: open Settings (gear icon) and set the memory slider in the Java and memory section. Each instance can override it in its own settings.

Open Options, then Video Settings. These are the settings with the biggest effect, under their 26.3 names:

Mods give the biggest gain, often more than any setting. They need a mod loader: Fabric (how to install Fabric) or NeoForge (how to install NeoForge and Forge). On 30 October 2026, all of these have 26.3 versions on Modrinth for both loaders:

• Sodium: replaces the rendering engine to raise frame rates and reduce micro-stutter. Version 0.9.2 for 26.3 came out on release day, 15 September 2026.
• Lithium: optimizes game logic such as mobs and block updates, in singleplayer and on servers.
• FerriteCore: reduces memory usage, useful with big modpacks.
• Entity Culling: skips rendering entities and block entities you cannot see.
• ImmediatelyFast: speeds up how entities, particles, text, the HUD and maps are drawn.

Sodium has no Forge version. For shaders on top of Sodium, add Iris: how to install shaders with Iris and Sodium. OptiFine has no 26.3 build yet, see how to install OptiFine.

Minecraft 26.x requires Java 25. The launcher downloads its own copy, the Microsoft Build of OpenJDK 25, and uses it for every installation, modded ones included. Leave the Java executable field in More Options untouched: an older Java cannot start 26.x. You only need Java installed on your system to run installer files such as the NeoForge or Fabric installer, or to host a server.