RAID Capacity Calculator
Works out how much space an array gives you after redundancy.
Usable capacity
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Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
In binary units (powers of 1,024) —
Total raw capacity —
Storage efficiency — %
Disk failures always survived —
Reading this —
The formula
RAID 0 = n × size RAID 1 = size RAID 5 = (n − 1) × size RAID 6 = (n − 2) × size RAID 10 = n ÷ 2 × size
Every disk counts as the size of the smallest. File system overhead then takes a little more.
What to watch out for
The unit menu has both decimal TB and binary TiB, because drives are labelled in one and many systems report in the other. The data storage converter handles other figures.
Frequently Asked Questions
How much does RAID 5 give from four 8 TB disks?
24.00 TB, or 21.83 TiB.
How much does RAID 10 give from the same disks?
16.00 TB.