Estimate RAM, CPU, world size and storage for your Minecraft server
How much RAM to rent is the first question for anyone opening a Minecraft server, but world size is usually underestimated. This calculator estimates RAM, CPU cores, world size and total storage from the number of players, the world scope and the mod/plugin load. The key is separating world size from total storage: the world grows as players explore, and much more when you pregenerate the map over a large radius, which can reach tens of GB. Total storage adds headroom for backups, mod files and base server files on top of that. The values start from practical recommendations for Minecraft: Java Edition (around 2–4 GB for small servers, 6 GB or more for busy, modded servers), on NVMe SSD.
Unlike client-side hardware requirements, which Mojang documents, sizing a dedicated server is market practice: a fixed runtime base plus a cost per concurrent player, extra memory for the mod/plugin load, and a bit more for minigames or heavy redstone. This calculator uses that same logic, not an official table, which is why the result shows as a range (minimum and comfortable) instead of a single number.
Example: 20 concurrent players, a moderately explored world and a light mod load work out to 4 to 6 GB of recommended RAM and 3 CPU cores. Switching the world to pregenerated or the mod load to heavy pushes both RAM and cores up, the tool caps the recommendation at 8 cores because past that point, optimizing the server software (Paper, thread allocation) pays off more than simply adding CPU.
World size is just the region-file folder; total storage adds headroom for backups, the mod/plugin files and the base server files on top of that. For example, 8 players in a lightly explored world produce about 3.6 GB of world data, but the estimate's minimum total storage is 8 GB because of that headroom, even a small server needs spare room for its first full backup and the runtime files.
At the other extreme, 40 players with a pregenerated world, heavy mods and minigames enabled reach 44 GB of world alone and around 76 GB of total storage. Pregenerating the map over a large radius with tools like Chunky is what loads the disk the most, far more than the player count by itself.
Since version 26.1 (released March 2026, when Mojang switched to year.drop numbering), the Minecraft: Java Edition dedicated server requires Java 25, up from the Java 21 minimum that had held since 1.20.5. That is why this calculator recommends Java 25 as the runtime, servers still running older game versions (up to the 1.21.x line) keep working fine on Java 21.
The exception is heavy Forge/NeoForge modpacks: mod loaders typically need a few weeks to certify a new Java version after a jump like this, so check your modpack's supported Java version before upgrading the server. Paper and Spigot, running close to vanilla, tend to catch up to the game's required Java almost immediately.
Paste the code into your HTML and the tool shows up on your page, without J-Kit's navigation and ads. It still runs in the browser of whoever visits your site.
<iframe
src="https://jkit.tools/embed/en-US/minecraft-server-calculator"
width="100%"
height="600"
style="border:0"
loading="lazy"
title="Minecraft Server Calculator"
></iframe>These references help contextualize formulas, standards, APIs and limitations used on this page. They do not replace professional validation when a result has legal, financial, medical or operational impact.
Because the world is what grows most on disk, and it grows as players explore, not from the player count itself. A fresh world is a few MB; a heavily explored world, or one pregenerated over a large radius with tools like Chunky, can take tens of GB. That is why the tool asks for the world scope and shows that value separately from total storage.
A starting estimate, not an official requirement. World size depends heavily on how much is explored or pregenerated; total storage already includes headroom for backups, mods/plugins and server files. Heavy mods and plugins can need more. Always monitor real usage and adjust.
The estimate is computed locally in the browser; nothing is sent to servers.