Minecraft Server Requirements
How much RAM, CPU and disk a Minecraft server actually needs — plus the Java version each game version requires, and the ports to open.
The single most common question when hosting a Minecraft server is "how much RAM do I need?" The honest answer is: it depends on your edition, how many players you expect, and — by far the biggest factor — whether you run vanilla, plugins, or mods. This page breaks down the real requirements and gives you a table to match a RAM tier to your community.
RAM is the number that matters most
Minecraft servers are memory-hungry. Every loaded chunk, entity, and mod lives in RAM, so running out of memory is the most common cause of lag and crashes. Player slots are almost never the real limit — RAM is. A server "for 20 players" that only has 2 GB will stutter long before it fills up, while the same 20 players on 8 GB run smoothly.
Give the server dedicated RAM rather than sharing it, and do not allocate literally all available memory — the operating system and Java overhead need headroom. On FluxCraft each plan tier is a fixed RAM allocation, so you always know exactly what your world has to work with.
RAM-to-players table
Use this as a starting point. Modded servers need far more RAM per player than vanilla, and heavy modpacks can double these numbers:
| RAM | Vanilla / light plugins | Modded | Good for |
|---|---|---|---|
| 2 GB | Up to ~10 players | Not recommended | Friends group, vanilla survival |
| 4 GB | ~10–20 players | Small/light packs | Small plugin server (Paper/Spigot) |
| 8 GB | ~25–40 players | Medium modpacks | Active plugin server or ATM-style pack |
| 16 GB | 60+ players | Heavy modpacks (RLCraft, big AtM) | Large modded or public community |
| 32 GB | Large public servers | Very heavy packs / large map | Busy networks, several worlds |
| 48 GB | Networks | Multiple heavy packs at once | Multi-server networks and events |
Which Java version does your server need?
This trips up more new server owners than RAM does, because getting it wrong does not cause lag — it stops the server booting at all, with an "Unsupported class file major version" error and no obvious explanation.
Each figure below is a minimum, not an exact match: an older Minecraft runs fine on a newer Java, so 1.16 on Java 17 is no problem. The failure is always the other direction, a newer Minecraft on an older Java. Modded servers inherit the requirement of whichever game version their Forge or Fabric build targets.
| Minecraft version | Minimum Java |
|---|---|
| 26.1 and newer | Java 25 |
| 1.20.5 – 1.21.11 | Java 21 |
| 1.18 – 1.20.4 | Java 17 |
| 1.12 – 1.17 | Java 8 |
On FluxCraft the correct runtime is installed with the version you deploy, so this is one thing you do not configure. It matters if you self-host, or if you upload a world from a server running a different version.
Ports
Java Edition listens on TCP 25565 by default, and Bedrock Edition on UDP 19132 — different protocols, which is why a firewall rule copied from a Bedrock guide will not work for a Java server. If you enable the optional query protocol (used by server-list websites and monitoring tools), that runs on UDP 25565. Self-hosting means forwarding these on both the router and the OS firewall; on a managed plan they are opened at deploy time.
CPU: single-thread speed beats core count
Minecraft's server tick loop is largely single-threaded, so a CPU with high per-core (single-thread) performance matters more than a high core count. This is why a fast modern core outperforms many slow cores for one world. More cores help when you run several separate servers or use Paper's parallel world features, but for one busy world, clock speed and IPC win. Keeping the server tick at a healthy 20 TPS is the goal — drops below that are what players feel as lag.
Storage, bandwidth, and the rest
A vanilla world starts small but grows as players explore and generate chunks; modded worlds and backups need more disk. FluxCraft plans scale storage with the RAM tier — 20 GB on the 2 GB plan up to 150 GB on the 48 GB plan — which is ample for a world plus backups at every size. Bandwidth requirements are modest per player, but a public server with many concurrent players and a large view-distance adds up. View-distance and simulation-distance are two of the highest-impact settings you control: lowering them from the default can dramatically cut both RAM and CPU load on a busy server.
How to pick your plan
Estimate your peak concurrent players, then decide vanilla vs plugins vs mods, and size up one tier if you plan to grow or run a demanding modpack. It is always easier to start a tier higher than to fight constant lag. FluxCraft plans run from 2 GB to 48 GB and you can scale RAM up or down as your community changes, so you are never locked into an oversized plan.
Frequently Asked Questions
How much RAM do I need for a Minecraft server?
2 GB for vanilla with up to ~10 players, 4 GB for small plugin servers, 8 GB for medium modpacks or an active plugin server, and 16 GB or more for heavy modpacks like RLCraft or large All the Mods packs. RAM is almost always the first bottleneck, not the player slot count.
Which Java version does a Minecraft server need?
It depends on the game version: Java 25 for Minecraft 26.1 and newer, Java 21 for 1.20.5 through 1.21.11, Java 17 for 1.18 to 1.20.4, and Java 8 for 1.12 to 1.17. These are minimums — an older Minecraft runs fine on a newer Java, but a newer Minecraft on an older Java fails to start with an "Unsupported class file major version" error.
What port does a Minecraft server use?
Java Edition uses TCP 25565 by default and Bedrock Edition uses UDP 19132 — different protocols, so a firewall rule written for one will not work for the other. The optional query protocol used by server-list sites runs on UDP 25565.
How many players can a Minecraft server hold?
There is no fixed cap. Practically, a 2 GB vanilla server holds ~10 players, 8 GB can handle 25–40, and 16 GB supports 60+ — but mods, view-distance, and world size lower these numbers substantially.
Does CPU or RAM matter more for a Minecraft server?
RAM is usually the first bottleneck, but Minecraft's tick loop is largely single-threaded, so single-thread CPU speed strongly affects TPS (tick rate) on a busy world. You want both: enough RAM and a fast core.
How much RAM does a modded server need?
Far more than vanilla. Light packs are fine on 4 GB, medium packs want 8 GB, and heavy packs such as RLCraft or big All the Mods versions need 16 GB or more.
Right-size your server in seconds
Pick the RAM tier that matches your community and deploy in under 30 seconds. Scale up or down anytime as you grow — no lock-in, first month free.