RAID calculator

You can estimate RAID characteristics using this RAID calculator. Select the desired array layout, then enter RAID member disk capacities into the form fields.

Enter your data below
Array layout
Physical disk size (leave fields blank if you plan for less than five drives) Disk 1 GB
Disk 2 GB
Disk 3 GB
Disk 4 GB
Disk 5 GB
The results are available below
Total array capacity
Fault tolerance - Maximum anticipated number of simultaneous disk failures.
Space required to maintain fault tolerance information.
Slack - space loss due to drive size inequality; unusable in hardware implementations; may be combined into the separate array in software implementations.
Estimated transfer speed (theoretical estimation only applicable for sustained linear operations; very optimistic in most cases; take it with a grain of salt). Speeds are relative to the single member disk speed. Read speed
Write speed


  • Write speed of a RAID 5 depends upon the controller implementation heavily. The estimation of a write speed is thus not provided for a RAID5.
  • RAID1 setups involving more than two member disks are allowed. Additional "shadow" disks provide additional fault tolerance at the cost of storage overhead.
  • RAID10 survives any single disk failure and a half of double failures (depending on the assignment of the failed drives).