Minecraft Server RAM Calculator
How Much RAM Does a Minecraft Server Need?
A Minecraft server RAM calculator that sizes three plans for your setup.
What Will You Run?
Memory floors differ: modded needs the most.
What Your RAM Actually Pays For
On Java Edition the number you pick is the JVM heap size. Loaded chunks, every entity inside them, block entities such as chests and hoppers, and your mod or plugin state all live in that heap.
It is not a speed dial. How much RAM a Minecraft server needs is set by how much world it holds at once.
Inside the heap: Forge / NeoForge
20 concurrent players, illustrative split of what occupies memory
10GB used6 GB floor + 0.2 GB × 20 playersThe floor is what Forge / NeoForge needs with nobody online. Everything above it is world data your players pull in, then we round up to the nearest plan we sell, the 12 GB one.
rounds up to the 12 GB plan
- Server jar + JVM
3 GBServer jar + JVM · 3 GBThe Forge / NeoForge jar plus everything the JVM keeps for itself. It costs the same at one player as it does at 20, so it is the part you cannot tune away.
Fixed cost before anyone joins: the engine and its runtime.
- Mods / plugins loaded
3 GBMods / plugins loaded · 3 GBTypical for Forge / NeoForge: every mod or plugin is loaded and held before the first player connects. Doubling your list moves this number, doubling your players does not.
Resident from boot. Grows with the list, not the player count.
- Loaded chunks
2.5 GBLoaded chunks · 2.5 GBRoughly 62% of the 4 GB your players add (0.2 GB per player × 20 players). Players exploring in opposite directions each hold their own chunks, so this is the part that spikes.
One column per player, more when they spread out.
- Entities & block entities
1.5 GBEntities & block entities · 1.5 GBThe other 38% of the 4 GB your players add (0.2 GB per player × 20 players). Mob farms and dropped item piles push it up well beyond the average.
Mobs, items and every chest or hopper in a loaded chunk.
Loaded chunks
Each player pulls their own column of chunks into memory. Two standing together cost far less than two exploring in opposite directions.
Entities inside them
Mobs, dropped items, minecarts and every chest or hopper stay resident for as long as their chunk is loaded.
Code loaded alongside
Your mod or plugin list is resident before anyone joins. Five performance mods and two hundred content mods are not the same server.
- on time
- overran, never caught up
Plenty of free RAM, and the server still lags.
Tick processing is largely single threaded, so every node runs a Ryzen 9 9950X. Past 50 ms per tick the server falls behind no matter how much memory is spare.
That is a CPU and world-design problem, not a memory one. Read the tick graph before the memory graph.
RAM by Server Type
Same world, five engines, five sets of Minecraft server requirements. Set your player count and every floor moves with it.
The official server jar with no optimisations. It is the least efficient way to run Java Minecraft, so treat 4 GB as a floor rather than a comfortable number once you pass a handful of players. Sized here at 6 GB for 20 concurrent players.
Paper reuses vanilla logic more efficiently and gives you configuration control over entity limits, chunk loading and view distance. A Paper server will usually hold more players on the same RAM than vanilla will. Sized here at 6 GB for 20 concurrent players.
Fabric itself is light. What costs memory is the mod list on top of it. A Fabric server running only performance mods can sit near vanilla usage; one running 200 content mods cannot. Sized here at 8 GB for 20 concurrent players.
How much RAM a modded Minecraft server needs starts with the loader: Forge and NeoForge carry more overhead than Fabric before a content mod loads, so their floors start higher. Sized here at 10 GB for 20 concurrent players. See modded Minecraft server hosting.
The Bedrock dedicated server is written in C++ rather than Java, so it has no JVM heap to size and runs far leaner at the same player count. This is why the calculator sizes the two editions differently. Sized here at 3 GB for 20 concurrent players.
Roughly +0.1 GB per concurrent player on vanilla and plugin servers, +0.2 GB on modded ones where each player loads a heavier set of chunks, then rounded up, since the next plan down would thrash. Sizing is by concurrent players, never by whitelist length.
When More RAM Will Not Help
Past a point, adding memory stops helping and starts hurting. Two hard reasons why, and the one knob left once the heap is the right size.
The garbage-collector tradeoff
A larger heap takes the collector longer to sweep, and on Java that sweep pauses the server. A 32 GB heap on a world that needs 8 GB trades short frequent pauses for long infrequent ones, which players feel as periodic freezes rather than smooth play.
8 GB heap, right-sized
short, frequent, unnoticed
32 GB heap, oversized
rare, long, felt as a freeze
The 32 GB pointer cliff
Below 32 GB the JVM compresses object pointers to save space. Cross that line and pointers grow, so a 33 GB heap can hold less useful data than a 31 GB one. Worth crossing only when the world genuinely needs it, not as a precaution.
Bar length is useful data held, not heap size. More memory, less room.
Aikar’s flags
Aikar’s flags are the JVM startup flags most Minecraft servers run. They add no memory. They change how the collector spends what you already have, pushing it towards short frequent pauses rather than rare long ones. They live in the startup command, which you edit on the Startup tab in the panel.
G1GC, aimed at a pause target
The collector is told to keep pauses short rather than to finish the sweep as fast as it can.
Minimum heap set to the maximum
The JVM claims the whole heap at boot instead of growing into it while players are online.
Younger generation sized up front
Short-lived objects, which is most of what a tick creates, are cleared without touching the rest of the heap.
These are tick-rate symptoms, not memory ones
If you recognise any of these, work through the fix before you buy another tier. Check which mod is eating the tick first.
Chunks load slowly as players move
Lower simulation distance: it sets how far entities keep ticking.
Mobs freeze in place mid-air
Clear out oversized mob farms and cap entities per chunk.
Blocks reappear after you break them
The server is behind on ticks. Profile the tick before adding memory.
Periodic freezes on an already large heap
Shrink the heap instead of growing it, then re-measure.
Redstone and hoppers run visibly late
Split hopper chains and clocks, or move them out of loaded chunks.
Lag spikes only when players teleport or fly
Cap chunk generation per tick and pregenerate the destination area.
Frequently Asked Questions
How the recommendation is worked out, and what to do if it turns out to be wrong.
