Allocating RAM correctly

There is a stubborn myth that pouring RAM into Minecraft fixes lag. It almost never does — and over-allocating can make things worse. This page explains how much to give, how to set it in each launcher, and how to read the warning signs.

Fair play note: RAM tuning is a normal, allowed client tweak. Nothing here touches gameplay advantage. As always, banned items are cheat clients, x-ray, and autoclickers/macros — none of which this involves.

The short answer

Setup	Recommended RAM
Vanilla or light mods	4GB
Performance mods (Sodium etc.)	4GB
Shaders	6GB
Large modpack	6GB
”I have tons of RAM”	Still 4–6GB

For HarvestSeason — a tidy solo-island gamemode with a modern, optimized client — 4GB is plenty for the vast majority of players.

Why more isn’t better

This surprises people, so it is worth understanding.

• FPS does not come from RAM. Frame rate is about your renderer and settings — install Sodium and lower render distance to gain frames. RAM only stops the game lagging when it runs out of memory.
• Garbage collection scales with the pool. Java periodically pauses to clean unused memory (“garbage collection”). The bigger the memory pool, the more there is to sweep at once, and the longer those pauses can be. Those pauses show up as periodic micro-freezes — a momentary stutter every several seconds. Right-sizing keeps each cleanup small and quick.
• Your OS needs RAM too. Allocating most of your system memory to Minecraft starves Windows and your other apps, causing system-wide slowdown.

So the goal is enough, not maximum: give Minecraft what it needs to avoid running out, and no more.

How to set RAM in each launcher

Prism Launcher

1. Select your instance, click Edit → Settings.
2. Find the Java / memory section and tick Override.
3. Set Maximum memory allocation to 4096 MB (or 6144 MB with shaders).
4. Leave minimum lower or matched. Save.

See the full setup in Prism Launcher + Fabric setup.

Lunar Client

1. Open Lunar’s launcher settings (gear icon).
2. Find Java / RAM Allocation (a memory slider).
3. Set it to 4GB (6GB with shaders). Apply.

More in Lunar Client setup.

Official (vanilla) launcher

1. Open the Minecraft Launcher, go to Installations.
2. Hover your installation, click the … menu, choose Edit.
3. Click More Options to reveal JVM Arguments.
4. Find the -Xmx value (e.g. -Xmx2G) and change it to -Xmx4G. Save.

-Xmx is the maximum memory. -Xmx4G means 4GB. That is the only value you usually need to touch.

Modrinth App

Open the instance’s settings and set the memory there; the layout mirrors the others — a single max-memory field.

Garbage collection basics (optional reading)

You do not need to tinker with garbage-collection flags. Modern Minecraft and the launchers above ship sensible defaults (the G1 collector), and for a 4–6GB heap those defaults are fine. Resist the urge to paste long lists of “optimized JVM flags” from old forum posts — many are outdated, target huge heaps, or can hurt more than help on a right-sized allocation. If you keep RAM at 4–6GB, the defaults already do the right thing.

Warning signs

Signs of too little RAM:

• The game freezes hard or crashes with an “Out of memory” error.
• Severe, worsening stutter the longer you play a session.
• Frequent long pauses on screens with lots of items.

If you see these, bump up by 1–2GB.

Signs of too much RAM:

• A rhythmic micro-stutter every several seconds even on a strong PC (the garbage-collection pause).
• Your whole system feels sluggish while Minecraft runs because other apps are starved.

If you see these, lower your allocation back toward 4GB.

Neither? You are right-sized. Leave it.

A reality check on FPS

If your real problem is low frame rate (not crashes or out-of-memory stutter), RAM is the wrong lever. Do this instead:

1. Lower render distance to 8–12 chunks.
2. Install Sodium or Fabulously Optimized.
3. Apply the recommended video settings.

Those three steps fix far more “lag” than any RAM change.

What’s next

Pair your right-sized RAM with the best video settings, and if you have not yet, install essential performance mods.