How to use this tool
Enter installed drive count, drive capacity, hot spares and RAID layout; plan backups separately.
Enter your details
All defaults are editable planning assumptions. Use actual product specifications and site conditions where possible.
How the estimate works
Count active equal-sized drives after hot spares. RAID 1 mirrors onto two or more active drives and provides one drive of nominal capacity; RAID 5 subtracts one, RAID 6 subtracts two, and RAID 10 uses half. RAID 0 has no redundancy.
Where product limits or site conditions matter, confirm them against the exact model and installation before buying.
Understanding your result
Usable capacity is lower than the sum printed on the drives because the selected RAID layout reserves space for redundancy. It can keep a system running through some drive failures, but deletion, theft and ransomware still need separate backup.
Choosing the right equipment
Check that the NAS supports the selected RAID mode, drive sizes and expansion path. Use compatible drives and plan a second backup destination for files you cannot replace.