Server RAM Calculator

Work out how much memory a host needs before you order it.

What you provide

A minimal Linux host needs about 1 GB. Windows Server and a monitoring stack need considerably more.

Memory the kernel uses to cache disk. On database and file servers this should be generous.

Result

32 GB covers 8 instances with room to spare

Two constraints decide the module layout rather than the total. Channel population matters: a two-socket board wants memory in matched sets across every channel, and filling half of them costs real bandwidth even when the capacity is right. And modules per channel affect the clock, so four large modules usually run faster than eight small ones at the same total. Check the board's population table before ordering, since the same 32 GB can be a good configuration or a slow one.

Diagnostic telemetry
Operating system
2.0 GB
Workloads8 × 2 GB
16.0 GB
Filesystem cacheMemory the kernel uses for page cache, not wasted
4.0 GB
With 25% headroom
27.5 GB
Order this much
32 GB

What this cannot tell you

  • A sizing estimate from what you enter. It cannot measure your workload, and a working set is genuinely hard to guess before you run something.
  • It says nothing about which modules to buy. Channel population and modules per channel affect real bandwidth and clock speed, and the board manual is the authority on both.

Take this with you

Server RAM Calculator on RunTheTests — free browser-based sysadmin tools, no sign-up.