"How much RAM do I need?" is the wrong first question for a modded server. The right one is "which pack, how many players, and how far are they spreading out?" All the Mods 10 will not even finish loading on 6 GB. RLCraft runs happily on the same 6 GB that chokes ATM10, because it is a different kind of heavy.
This page has the real numbers for every popular pack in 2026, where they come from, and what to do when your server is still lagging after you threw RAM at it.
The quick answer, by pack
Server-side RAM, assuming a normal survival world and default view distance. Client requirements are lower for everything here except ATM10.
| Modpack | Mods | 2-5 players | 5-15 players | Notes |
|---|---|---|---|---|
| All the Mods 10 | 400+ | 10 GB | 12-14 GB | Will not load below ~10 GB. Java 21 required |
| Beyond Depth | 300+ | 8-10 GB | 12 GB | Dimension-heavy: storage grows fast |
| Enigmatica 9 | 250+ | 8 GB | 10 GB | 6.5 GB is the documented floor, not a target |
| DawnCraft | 200+ | 6 GB | 8-10 GB | Entity-heavy combat: CPU matters more than RAM |
| RLCraft | 170+ | 6 GB | 8 GB | Old but relentless; mob AI is the real load |
| SkyFactory 4 | 200+ | 5-6 GB | 8 GB | Skyblock: tiny world, light on chunks |
| Pixelmon | 1 huge mod | 4-6 GB | 8 GB | One mod, thousands of entities |
| Vanilla / Paper | 0 | 2 GB | 4 GB | For contrast: this is what "light" looks like |
Mod count is a bad predictor on its own. Pixelmon is a single mod that can outweigh a 150-mod tech pack, because what costs memory is entities, dimensions, and loaded chunks, not the number of jar files. Use the table, not arithmetic on mod counts.
All the Mods 10: the one everyone asks about
ATM10 is the most downloaded pack of 2026 and the most common source of "my server won't start" threads. The official requirements are unusually explicit, which helps:
| Players | RAM | CPU | Storage |
|---|---|---|---|
| 2-5 | 10 GB | 4 cores, 3.5 GHz | NVMe SSD, 30 GB |
| 5-15 | 12-14 GB | 6 cores, 3.8 GHz | NVMe SSD, 50 GB |
| 15+ | 16+ GB | 8+ cores, 4.0+ GHz | NVMe SSD, 100+ GB |
Three things people get wrong with this pack:
- Java 21 is mandatory. Not "recommended". The pack will refuse to launch on older runtimes, and the error message is not obvious about why.
- 8 GB is not "close enough". With 400+ mods, the pack can spend so long in garbage collection that the server looks frozen rather than slow. There is no gradual degradation here, it just stops behaving.
- Storage is not an afterthought. ATM10 generates several dimensions. A world that starts at 2 GB can pass 30 GB within a few months of active play.
Why your server still lags after adding RAM
This is the most common follow-up, and it is where most guides stop being useful. Adding memory fixes exactly one problem: not having enough memory. It does nothing for the other three causes.
Single-thread CPU speed. Minecraft's main game loop is largely single-threaded. A 16-core server at 2.4 GHz will lose to a 6-core at 4.0 GHz for the same pack. When you compare hosting plans, clock speed is the number that matters, and it is the one most providers bury.
Entity count. DawnCraft and RLCraft are CPU-heavy rather than RAM-heavy because mob AI and pathfinding run every tick. A mob farm or a stacked-entity chunk will tank TPS on a server with plenty of free RAM. Our mob switch guide covers suppressing spawns you do not need.
View and simulation distance. Every player is loading a bubble of chunks around them, and simulation distance decides how much of that bubble actually ticks. Dropping simulation distance from 10 to 6 often recovers more TPS than 4 GB of extra RAM. The render vs simulation distance guide explains which one to cut first.
Over-allocation, genuinely. Giving a 10 GB pack 24 GB does not make it faster; it makes each garbage collection pause longer and more noticeable. Allocate what the pack needs plus headroom, not everything the box has. This is covered in depth in our server RAM guide.
Do not allocate all of the server's RAM to Java. The operating system needs its own headroom, and on a rented box you are usually sharing with the panel and backup processes. Leave at least 1-2 GB unallocated, more on a machine you also use for other things.
JVM flags worth setting
Once the pack has enough memory, the remaining wins come from how Java uses it. Aikar's flags remain the standard for modded servers in 2026: they tune G1GC to collect in short, frequent pauses instead of rare long freezes, which is exactly what a tick-based game wants.
The JVM flags guide has the full string and what each part does. If you only take one thing: set -Xms and -Xmx to the same value, so the heap does not resize under load.
Self-hosting vs renting
Running a modpack server on your gaming PC works, with two caveats that catch people out: the server competes with the game for the same CPU cores, and it is only online while your machine is. For a pack like ATM10, you need a machine with 32 GB total to comfortably give the server 12 GB and still play on it.
The honest cutoff: if you want the server up when you are not, or you have more than about five regular players, renting stops being the lazy option and starts being the cheaper one once you count electricity and the machine you are not using for anything else.
What to check before you buy
Hosting plans are sold on RAM because it is the easiest number to compare. These matter as much or more for a modded server:
- CPU clock speed, not core count. Ask for the actual GHz, and be wary of plans that will not tell you.
- NVMe storage, not shared HDD. Chunk loading is disk-bound, and a modded world is thousands of small reads.
- Modpack presets. A one-click ATM10 install saves an afternoon of manual jar wrangling and version mismatches.
- Room to upgrade. Modded worlds grow. Starting on a plan you can bump without migrating is worth a small premium.
Our RAM calculator turns a player count and mod load into a plan size, and the hosting comparison ranks providers on real high-entity performance rather than marketing copy.
FAQ
How much RAM do I need for an All the Mods 10 server?
10 GB for 2-5 players, 12-14 GB for 5-15, and 16 GB or more beyond that. The pack will not load properly below roughly 10 GB, and it requires Java 21.
Is 8 GB enough for a modded Minecraft server?
For mid-weight packs like RLCraft, DawnCraft, or SkyFactory, yes. For 400-mod kitchen-sink packs like All the Mods 10, no: it will either fail to start or spend most of its time in garbage collection.
Does more RAM make a Minecraft server faster?
Only up to the point where the pack has enough. Past that, extra RAM makes garbage collection pauses longer, not shorter. Once memory is sufficient, the bottleneck moves to single-thread CPU speed, entity count, and simulation distance.
What CPU do I need for a modded server?
Prioritise clock speed over core count: Minecraft's main loop is largely single-threaded. Aim for 3.5 GHz or better for mid-weight packs and 3.8-4.0 GHz for ATM10-class packs. Cores help with concurrent chunk loading and other players, but they do not fix a slow tick.
Can I run a modpack server on my own PC?
Yes, if the machine has enough total RAM to give the server its share and still run your game, and you accept that the server is offline whenever the PC is. Anything beyond a handful of friends is usually cheaper and less annoying to rent.
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