How much RAM should you allocate to Minecraft?
Pick your modpack and how much RAM your PC has. You get the number to set in your launcher, using the pack authors' own figures where they publish them.
We leave 4 GB free for Windows and background apps. That is a rule of thumb, not an official number.
Vanilla (no mods): the pack authors list 2 GB minimum and 4 GB recommended for the game client.
- Minecraft Launcher: Installations, Edit, More options, change
-Xmx2Gto-Xmx4G. - CurseForge app: Settings, Minecraft, Allocated Memory.
- Prism / MultiMC: Settings, Java, Maximum memory.
- FTB App and Modrinth App: the pack or global settings, Memory.
More is not always better: too much memory makes Java pause longer to tidy up. This is for playing the pack, not for hosting a server (see the server calculator).
FAQ
How much RAM should I allocate to Minecraft?
Vanilla runs well on 2 to 4 GB. Large modpacks list 6 to 10 GB or more. Never give it all your RAM: leave a few gigabytes for Windows and background programs.
Is allocating more RAM always better?
No. Past what the pack needs, extra memory makes the Java garbage collector pause for longer, which can cause stutters. Aim for the recommended amount, not the maximum.
Are the official figures for a server or for playing?
Mostly for playing: they are the game-client figures from the pack's page or launcher. Hosting a server for a group usually needs more, so use the server calculator for that.
How do I change the allocation?
In the Minecraft Launcher edit the installation and change the -Xmx value. In the CurseForge, Prism, FTB and Modrinth apps it is in the settings under Memory or Java.
Hosting a server instead? Use the Minecraft Server Calculator or read each pack's server page, for example All the Mods 10.