How much RAM should I allocate to Minecraft for a modpack?
How much RAM to allocate to modded Minecraft, how to allocate more in CurseForge, Modrinth App and Prism, why more isn't always better, and what servers need.
· 4 min readThe short answer
Allocate RAM to Minecraft by pack size. Most modpacks need 4 GB of RAM if small (under about 50 mods), 6 GB if medium (50 to 150 mods) and 8 GB or more if large or heavy on world generation. Don't give Minecraft more than about half your computer's memory: too much can make stutters longer. Servers need their own memory on top, growing with players.
Your modpack freezes for a second every few seconds, or crashes with OutOfMemoryError, and someone on a forum tells you to "just give it more RAM". How much more? And how much is too much? Here's a straight answer.
How much to give each size of pack
| Pack | Mods | Memory to start with |
|---|---|---|
| Vanilla or small | under about 50 | 4 GB |
| Medium | about 50 to 150 | 6 GB |
| Large, or heavy on tech and world generation | 150+ | 8 GB, sometimes more |
These are starting points, not rules. The number of mods matters less than which mods: a pack with a handful of big world-generation and tech mods can need more than a pack of 200 small tweaks.
How to tell if you need more
You probably need more memory if:
- The game crashes with
OutOfMemoryErrorin the crash report. - It hangs on the loading screen near the end of loading.
- It freezes briefly but regularly while you play, even standing still in a base you've already explored.
If the freezes only happen when you fly into new chunks, that's world generation, not memory. More RAM won't fix it; a lighter world generation mod or pre-generating the world will.
Why more isn't always better
Giving Minecraft 16 GB "to be safe" can make it worse. Java cleans up unused memory in batches. With a huge allocation, garbage piles up between clean-ups, and the occasional full clean-up takes longer, which shows up as a stutter. Your computer also needs memory for itself, the launcher, your browser and voice chat.
A good rule: never give Minecraft more than about half of your computer's total RAM, and only as much as the pack actually uses.
How to allocate more RAM in CurseForge, Modrinth App, Prism and ATLauncher
Every launcher has a memory setting, usually in the pack's (or instance's) settings:
- CurseForge app: Settings, then Minecraft, then the Java memory slider. You can also set it per profile.
- Modrinth App: the instance's settings, under Java and memory.
- Prism Launcher: edit the instance, then Settings, then the Java tab; tick Memory, then set the maximum memory allocation.
- ATLauncher: the instance's settings, under Java/Minecraft.
Set the maximum. Leave advanced Java arguments alone unless you know why you're changing them. For screen-by-screen steps in each launcher, see how to allocate more RAM to Minecraft.
What about a server?
A server needs its own memory, separate from players' games. It runs the world for everyone, so it needs more as more people join and spread out, because each player keeps their own patch of the world loaded. For a small group on a medium pack, 6 to 8 GB is a common starting point, with more for bigger groups or heavy packs.
Pre-generating the world (with a mod like Chunky) before everyone joins takes a lot of strain off a server, because it does the expensive world generation once, up front.
Or let the pack tell you
Guessing is the problem. Packspire doesn't guess: during every build, a real game client joins a world with 4 GB, and again with 6 GB if that runs out, and the test server's memory use is measured during play. The pack's page tells players what to set in their launcher and tells whoever hosts the server what it needs. Every pack also comes with a set of performance mods that have been tested together.
Build a pack that tells you its own memory. If your pack is crashing for other reasons, see how to find the mod causing a crash.
Frequently asked questions
Is 8 GB of RAM enough for a modpack?
Allocating 8 GB to Minecraft is enough for nearly all modpacks. A computer with 8 GB in total can usually give a pack 4 GB, which suits small and some medium packs.
Can allocating too much RAM slow Minecraft down?
Yes. Java clears unused memory in batches, and with a very large allocation the occasional full clean-up takes longer, which shows as a stutter. It also starves the rest of your computer.
How do I allocate more RAM in the CurseForge app?
Open Settings, then Minecraft, and move the Java memory slider; individual profiles can override it in their own settings. Other launchers have the same setting in the instance's Java options.
How much RAM does a modded Minecraft server need?
For a small group on a medium pack, 6 to 8 GB is a common starting point. Add more for bigger groups and heavy packs, and pre-generate the world to cut the load.
