RAID Capacity
Estimate conventional RAID usable capacity with equal-size disks.
Your numbers
Usable nominal capacity
Before filesystem, controller metadata, spare disks and reserved capacity. RAID is not a backup.
Scenario comparison
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Formula
With N equal-size disks of S TB, usable capacity is NS for RAID0, S for RAID1, (N−1)S for RAID5, (N−2)S for RAID6, and NS/2 for RAID10. Redundancy does not replace a backup.
Estimate conventional RAID usable capacity with equal-size disks.
Worked example
- Disk count
- 4
- Smallest disk capacity (TB, decimal)
- 4
- RAID level
- RAID 5
- Usable nominal capacity
- 12 TB
- Raw nominal capacity
- 16 TB
Scope and limitations
Before filesystem, controller metadata, spare disks and reserved capacity. RAID is not a backup.
Inputs are checked for missing values and allowed ranges. A result outside the finite numeric range is not displayed. Rounding affects display, while the calculation uses the model’s numeric precision.
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Formula version: b2581d8d1987 · Example checked: