A RAM calculator that tells you to buy less

Ask a hosting company how much memory your server needs and you have asked a question they have a commercial interest in answering wrongly. So here is a calculator, free and without an account, that will regularly tell you to spend less than we would like:

The ChunkyHost RAM calculator

Pick your server type, how many people play at once, and — for modded servers — your mod count and view distance. It gives you a figure, a line-by-line breakdown of how it got there, and Aikar’s flags you can paste straight into a start command.

Why a calculator, and not a table

Tables exist. The problem is that every one of them is wrong for someone, because the number depends on things a table cannot see: whether you run plugins or mods, how many of each, how far your view distance reaches, and how many chunks your players keep loaded between them.

A calculator can ask. It can also do the thing a table never does, which is say “that is enough, stop”.

The one thing it will not do

It will not tell you that more memory fixes lag. It does not, and the calculator is built so it cannot imply otherwise.

Minecraft’s tick loop is largely single-threaded and CPU-bound. If your server is stuttering, you are almost certainly looking at a CPU, plugin or chunk-loading problem, and adding memory changes none of them. Memory stops your server crashing with an out-of-memory error; it does not raise your TPS. This is the single most common piece of bad advice in server hosting, and it is bad advice that happens to sell larger plans.

If your server is slow rather than crashing, profile it first — the RAM guide walks through reading a Spark profile and finding the mod or task that is actually eating the tick.

Where it is deliberately conservative

Two places, both on purpose:

• It rounds up, never down. A pack that runs comfortably in 6 GB on a quiet night can spike during world generation. Being told 8 GB and using 6 is an annoyance; being told 6 GB and crashing mid-build session is a lost evening.
• It caps out. Every server type has a ceiling, and past it the calculator stops adding and says so: “past this, extra RAM sits idle and does nothing for TPS.” That is the sentence a hosting company is not supposed to write.

It also shows its working — the figure comes with the base, the per-player load and the modded overhead itemised, so you can disagree with any line of it.

The rules it is built under

It is free, permanently. There is no account, no email wall, no watermark, and no “upgrade for the full result” step. If it recommends a figure smaller than any plan we sell, it says so anyway.

That is not charity — it is the only version of this tool worth publishing. A calculator from a host that always recommends the next plan up is an ad with a form on it, and everyone can tell.

The rest of our free tools are on the tools page, under the same rules.