Free RAID Calculator - Capacity, Fault Tolerance, Speed for RAID 0/1/5/6/10/50/60

RAID Calculator

Pick a RAID level, enter the number of drives and drive size, and get usable capacity, fault tolerance (how many drives can fail without data loss), and read / write speed multipliers. Covers RAID 0, 1, 5, 6, 10, 50, and 60 — the levels you'll actually use in home NAS, workstation, and server builds.

RAID configuration

RAID level

Number of drives

Drive size

Unit

Usable capacity12.00 TB

16.00 TBRaw capacity

25.0%Parity overhead

1Drives can fail

4xRead speed factor

3xWrite speed factor

RAID level comparison at your drive count

Level	Usable	Overhead	Fault tolerance	Min drives

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RAID Calculator guide

How to use the RAID Calculator accurately

The calculator uses the standard RAID capacity formulas for each level: RAID 0 gives n × D (all drives, zero redundancy); RAID 1 gives D (all drives mirror the same data); RAID 5 gives (n-1) × D (one drive's worth lost to parity); RAID 6 gives (n-2) × D (two drives lost to dual parity); RAID 10 gives (n/2) × D (mirrored...

01 How The RAID Calculator Works The calculator uses the standard RAID capacity formulas for each level: RAID 0 gives n × D (all drives, zero redundancy); RAID 1 gives D (all drives mirror the same data); RAID 5 gives (n-1) × D (one drive's worth lost to...

02 Choosing A RAID Level In 2026 For home and prosumer builds, the conventional wisdom has shifted toward RAID 6 (or its ZFS equivalent, RAIDZ2) for any array built from drives 8 TB or larger.

03 RAID 10 vs RAID 5/6 For Performance The calculator's speed multipliers tell the story: RAID 10 has a write multiplier equal to n/2 (full speed on each mirror pair, striped across pairs), while RAID 5 has roughly (n-1) × 0.75 and RAID 6 roughly (n-2) × 0.5.

04 RAID Is Not A Backup Strategy The single most-repeated piece of storage advice holds: RAID protects against drive failure, not data loss. A ransomware attack encrypts every drive in your array simultaneously; a fire or flood takes them all out; a careless "rm...

raid calculator raid capacity calculator raid 5 calculator raid 10 calculator raid fault tolerance nas storage calculator

The calculator's speed multipliers tell the story: RAID 10 has a write multiplier equal to n/2 (full speed on each mirror pair, striped across pairs), while RAID 5 has roughly (n-1) × 0.75 and RAID 6 roughly (n-2) × 0.5.

RAID Calculator FAQ

Common raid calculator questions

Is RAID 5 still safe with large drives?

For drives 8 TB or larger, most storage engineers now recommend RAID 6 over RAID 5. The reason is rebuild time: reconstructing a failed drive from parity can take 24-48 hours on a large array, during which a second drive failure would be catastrophic. RAID 6 tolerates a second failure mid-rebuild.

What is the difference between RAID 10 and RAID 5?

RAID 10 mirrors data across pairs, then stripes those pairs, delivering excellent random I/O performance but consuming 50% of raw capacity. RAID 5 stripes with a single parity drive, giving better capacity efficiency (~83% on 6 drives) but slower writes due to the parity write penalty.

Does RAID replace backups?

No. RAID protects against physical drive failure within its parity budget. It does not protect against ransomware, accidental deletion, filesystem corruption, fire, flood, or theft - all of which can affect every drive in the array at once. Always maintain separate backups on top of RAID, following the 3-2-1 rule.

What is the minimum number of drives for each RAID level?

RAID 0 and RAID 1 need 2 drives. RAID 5 needs 3. RAID 6 needs 4. RAID 10 needs 4 (and always an even number). RAID 50 needs at least 6 (two groups of 3). RAID 60 needs at least 8 (two groups of 4). More drives give you more capacity and often better performance, but also more opportunities for a drive to fail.

Checklist

Utility checks to confirm

How The RAID Calculator Works The calculator uses the standard RAID capacity formulas for each level: RAID 0 gives n × D (all drives, zero redundancy); RAID 1 gives D (all drives mirror the same data); RAID 5...
Choosing A RAID Level In 2026 For home and prosumer builds, the conventional wisdom has shifted toward RAID 6 (or its ZFS equivalent, RAIDZ2) for any array built from drives 8 TB or larger.
RAID 10 vs RAID 5/6 For Performance The calculator's speed multipliers tell the story: RAID 10 has a write multiplier equal to n/2 (full speed on each mirror pair, striped across pairs), while RAID 5 has roughly...