RAID Calculator

Calculate disk capacity, performance, and fault tolerance for advanced RAID configurations.

Usable Capacity (TiB)
0 TiB
0 TB
Protection (Parity) Space
0 TiB
0 TB
Fault Tolerance (Disks)
0
Drive(s) per group
Raw Capacity
0 TiB
0 TB
Usable (0%)
Parity (0%)
Note: Manufacturers calculate capacity in Base-10 (1 TB = 1000 GB). Operating systems use Base-2 (1 TiB = 1024 GiB). This calculator shows the true OS usable (TiB) values.

Visual Architecture Layout

Data Disk
Parity (Protection) Disk
Hot Spare Disk

RAID Architectures & Technical Specs

When choosing the most suitable RAID level for your enterprise storage infrastructure, consider your performance, capacity and fault-tolerance requirements.

RAID 0 (Striping)

Splits data into blocks across disks (striping), writing and reading simultaneously. No capacity loss, but any single disk failure destroys all your data.

Performance: Highest
Tolerance: None (0 Disks)
Min. Disks: 1

RAID 1 (Mirroring)

Mirrors the same data to two disks. Excellent data safety, but exactly half (50%) of the total disk capacity is lost.

Performance: High Read
Tolerance: 1 Disk
Min. Disks: 2

RAID 5 (Parity)

Distributes data and a recovery (parity) block across the disks. The most popular, ideally balanced architecture for storage, performance and safety.

Performance: High
Tolerance: 1 Disk
Min. Disks: 3

RAID 6 (Dual Parity)

Works like RAID 5 but writes a double parity block. Tolerates 2 simultaneous disk failures. Essential for large disks due to long rebuild times.

Performance: Medium (Write)
Tolerance: 2 Disks
Min. Disks: 4

RAID 10 (1+0 Nested)

Combines mirrored (RAID 1) disk groups as stripes (RAID 0). High capacity loss (50%) but unmatched for high I/O and database performance.

Performance: Excellent
Tolerance: 1 Disk per Group
Min. Disks: 4

RAID 50 / 60 (Nested Parity)

Combines multiple RAID 5 or RAID 6 groups into one large pool (RAID 0). Designed for enterprise-grade, massive storage systems.

Performance: Very High
Tolerance: 1 or 2 per Group
Min. Disks: 6 / 8

What Is a RAID Calculator?

IzHost RAID Calculator is a free tool that, given the number of disks, disk capacity and RAID level, computes your usable capacity, the space reserved for parity/protection, how many disk failures you can survive, and the read/write performance multiplier. Plan your server and storage infrastructure correctly before you buy.

RAID (Redundant Array of Independent Disks) combines multiple disks into a single logical unit to provide performance, capacity efficiency or data safety (redundancy). Choosing the right RAID level depends on the balance between budget, performance needs and acceptable risk — this calculator backs your decision with hard numbers.

Frequently Asked Questions

Which RAID level should I choose?
RAID 1/10 suits high safety and performance (databases); RAID 5 a capacity/safety balance; RAID 6 extra safety on large disks; and RAID 0 only scenarios needing maximum speed with no redundancy. The calculator helps you compare capacity and fault tolerance for each level.
Why is my usable capacity less than the sum of the disks?
RAID levels reserve part of the space for redundancy (mirror) or parity for data safety. For example, RAID 5 uses the capacity of one disk and RAID 6 two disks for parity; RAID 1/10 reserves half the capacity for mirroring.
Does RAID replace backups?
No. RAID provides uptime against disk failure but is not a backup. Accidental deletion, ransomware, file corruption or multiple disk failures can destroy your data. Always use regular backups alongside RAID.
What is the difference between TB and TiB?
Manufacturers calculate capacity in base-10 (1 TB = 1000 GB); operating systems show it in base-2 (1 TiB = 1024 GiB). So a 1 TB disk appears as roughly 0.909 TiB in the OS. The calculator shows the true usable (TiB) values.
How many disk failures can I survive?
RAID 0: none (one failure loses all data). RAID 1/5: 1 disk. RAID 6: 2 disks. RAID 10: one disk per mirror group (possibly more if from different groups). The calculator clearly shows the fault tolerance for your chosen setup.
Should I choose RAID 5 or RAID 6?
RAID 6 is recommended on large (4 TB+) disks, because during a rebuild after one failure the risk of a second disk failing is high, and RAID 6 protects against that. On smaller arrays, RAID 5 can be more capacity-efficient.