RAID calculator

Usable space and protection of your disks.

What it does

Gives the usable space and the protection of disks put together in RAID: type the number of disks, the size of one disk and the RAID level.

RAID 0: all the space, all the speed, no protection. RAID 1: every disk is a copy. RAID 5: one disk’s worth of parity, one failure allowed. RAID 6: two disks of parity, two failures. RAID 10: mirrored pairs, half the space.
Disk makers count in TB (10¹² bytes); Windows and most NAS show TiB (2⁴⁰ bytes): a 4 TB disk shows as 3.64 TiB. The tool gives both.
The drawing shows each disk as a column: data, parity (spread over all the disks in RAID 5 and 6) or copy.
The speeds are an order of magnitude, in “times one disk”, for big files.

All the disks are counted at the size of the smallest. And RAID is not a backup.

Free, no account, nothing is sent: it runs in your browser, even offline.

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