Modded Minecraft is far more demanding than vanilla. By default, the CurseForge app only hands Minecraft a small amount of memory, so large modpacks can stutter, freeze, or crash with an Out of Memory error. This guide shows you how to give Minecraft more RAM in the CurseForge app, both globally and for a single modpack.

Note

This changes the RAM on your own computer's game client, not on a multiplayer server. If the server itself is lagging or crashing, see What About Your Server's RAM? near the end.

Before You Start

Check your total RAM. On Windows, open Task Manager, go to Performance, then Memory. On a Mac, click the Apple menu and choose About This Mac.
Only allocate RAM you actually have. Never give Minecraft all of it. Leave at least 3 to 4 GB free for your operating system and anything else running.
64-bit Java is needed for large allocations. To go above 4 GB, CurseForge has to be running 64-bit Java. Modern versions of the app install and use it by default, but if a profile is pointed at 32-bit Java you'll be capped near 2 GB and heavy modpacks can crash with a heap error. You can check or set the runtime under Java Settings.

Allocate RAM for All Modpacks (Global)

This sets the default memory for every modpack that does not have its own custom value.

1
Open the CurseForge app.
2
Click the Settings (gear) icon in the bottom-left corner.
3
Under Game Specific, select Minecraft.
4
Find the Java Settings section and locate the Allocated Memory slider.
5
Drag the slider to your desired amount. Changes save automatically.

Allocate RAM for a Single Modpack

Use this when one heavy pack needs more memory but you don't want to raise it for everything else.

1
Open the CurseForge app and go to My Modpacks.
2
Hover over the modpack you want to change, click the three dots, then choose Profile Options.
3
Turn on Custom RAM Allocation.
4
Set the maximum memory for this pack using the slider.
5
Click Done to save.

How Much RAM Should You Allocate?

Your setup	Recommended RAM
Vanilla or a few light mods	`2` to `4` GB
Small modpacks (up to ~75 mods)	`4` to `6` GB
Large modpacks (100+ mods, shaders)	`6` to `8` GB
Very heavy or "expert" packs (200+ mods)	`8` to `10` GB

Caution

More is not always better. Allocating too much RAM can actually cause more lag and longer stutters, because Java has to pause the game to clean up unused memory (a process called garbage collection). For most players, 6 to 8 GB is plenty, and going above 10 to 12 GB rarely helps.

Tip

Match your allocation to your total RAM. With 16 GB installed, 6 to 8 GB for Minecraft is a safe ceiling. With only 8 GB installed, keep Minecraft at 3 to 4 GB so your system stays responsive.

Still Crashing?

Double-check that you did not allocate more RAM than your computer physically has.
Close other memory-heavy apps, such as browsers with many tabs, streaming software, or other games.
Update your graphics drivers.
Lower in-game settings such as render distance and graphics quality.

What About Your Server's RAM?

Allocating RAM in the CurseForge app only affects your own game client. It has no effect on a dedicated server that you and your friends connect to. Server RAM is set on the host instead.

On a Game Host Bros Minecraft server, your plan determines how much RAM is available, and larger modpacks need more of it. If your server is the thing lagging or crashing while generating a modded world, you likely need to upgrade your server. To install the matching modpack on the server itself, follow our installing modpacks guide.

If you get stuck at any point, just reach out to a bro on Discord.

How to Allocate More RAM in the CurseForge App