RAID Storage Calculator

Estimate usable array capacity from disk count, disk size and RAID level.

About the RAID Storage Calculator

Compare approximate usable capacity for common RAID layouts using equal-size disks.

How to use it

  1. Enter the disk count and capacity of each disk.
  2. Choose GB or TB and select a RAID level.
  3. Calculate to see usable capacity and redundancy guidance.

Capacity logic

RAID 0 uses all disks, RAID 1 uses one mirrored-disk capacity, RAID 5 reserves one disk, RAID 6 reserves two, and RAID 10 uses half the raw capacity.

Example

Four 2 TB disks in RAID 5 provide an estimated 6 TB of usable capacity before filesystem and controller overhead.

Important note

RAID is not a backup. Actual usable space can be lower because of drive-size conventions, metadata, filesystem formatting, controller behavior and reserved capacity.