TrueNAS calculators and planning tools
Start with the resource you need to size: disk capacity or system memory. These browser calculators let you compare a proposed build before choosing components.
TrueNAS pool capacity calculator
Use the TrueNAS ZFS pool calculator to compare mirrors and RAIDZ layouts before buying drives. Enter disk size and vdev count, then inspect estimated capacity, redundancy, padding and free-space allowances. Save a shareable layout to revisit a purchase decision. Read the explanation below the widget for assumptions that affect the result.
TrueNAS RAM and ARC calculator
The network's TrueNAS RAM sizer at TrueNAS Hub estimates a memory budget for storage services and container workloads, with an ARC allowance and network throughput ceiling. Use it alongside the hardware requirements guide when deciding how much memory to buy. Its workload allowances are planning assumptions; check your applications' actual requirements.
ZFS and RAIDZ calculator
For unbranded OpenZFS planning, open ZFS Storage Hub's ZFS and RAIDZ calculator. Compare disk count, drive capacity and parity choices in a separate pool estimate. Use it when your system is not specifically a TrueNAS build, and read its model assumptions before comparing the result with this site's calculator.
A capacity result is only the storage budget. Use the TrueNAS RAM requirements guide to account for services and applications, then plan snapshots and a separate backup destination.