Infrastructure / FREE BROWSER TOOL
RAID Capacity Calculator
Estimate theoretical RAID array usable capacity and disk failure tolerance for equal-sized disks, in TB and TiB.
✓ Free to use✓ Runs locally✓ No account needed
Run the tool
Enter the values below to calculate or convert.
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Using the raid capacity calculator
Select RAID level and enter the number of same-size disks and their marketed capacity in decimal terabytes. Calculations assume equal-sized disks.
Real-world example
Example: 6 × 4 TB drives in RAID 6 produce roughly 16 TB of theoretical usable capacity.
Good to know
RAID protects against certain disk failures but is not a backup. Filesystems, metadata, spares, and vendor implementations can reduce usable capacity.
This tool is a planning aid, not a substitute for verifying values in vendor documentation or production configurations.