RAID Capacity Calculator
Enter your disk count and size to see usable capacity, redundancy and fault tolerance for RAID 0, 1, 5, 6 and 10.
Runs locally in your browser
Usable capacity
12.0 TB
Raw capacity16.0 TB
Redundancy overhead4.0 TB
Efficiency75%
Disk fault tolerance1
Single parity, one disk of overhead.
What is the RAID Capacity Calculator?
This calculator shows usable capacity, storage efficiency and how many drives can fail for the common RAID levels.
How to use it
- 1Enter the number of disks and the size of each disk.
- 2Pick a RAID level.
- 3Read usable capacity, efficiency and fault tolerance.
How it works
RAID 0 uses all disks (no redundancy). RAID 1/10 mirror pairs (50% usable). RAID 5 loses one disk to parity, RAID 6 loses two. Usable = (disks − parity) × size.
Limitations & notes
- Filesystem overhead and vendor formatting reduce real usable space.
- RAID is not a backup — it protects against drive failure, not deletion or corruption.
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