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Infrastructure & Storage

RAID Calculator

Compare usable storage and disk-failure tolerance for common RAID levels.

Calculations run in your browser. The tool does not send your inputs to a server.

01Your inputs

Local workspace

Start with the sample below, or enter your own values.

01 (0+1) mirrors two stripe sets; 10 (1+0) stripes mirror pairs. 3/4 use dedicated parity; 5/6 distributed parity; 50/60 stripe parity groups.
3/4/5 need at least 3 disks; 6 at least 4. 01 and conventional 10 require an even count of at least 4. 50/60 need at least 3/4 disks per group. Exclude hot spares.
Use the smallest disk size. Larger disks contribute only that much capacity in this model.
Used only by RAID 50 and 60. Enter at least two equal-sized groups; total member disks must divide equally. Leave the sample unchanged for other levels.

02Your result

Your result will appear here. Choose an action after checking your inputs.

A quick guide

How to use this tool

  1. Check the example and the unit beside each input.
  2. Enter your values and choose Calculate.
  3. Review the result and assumptions, then copy what you need.

Reset example restores the starting values. Clear removes text and number inputs, returns choices to their first valid option, and removes the result.

Reference guide

Explanation and worked examples

Four 4 TB disks in RAID 5 give 12 TB usable before formatting. RAID 01 and 10 have the same capacity but different failure behaviour. RAID 50/60 capacity depends on group count. RAID 2 Hamming ECC and vendor-specific layouts are outside this model.

Use in day-to-day IT work

Compare disk layouts when sizing a storage server.

Checks before applying the result

  • Six 4 TB disks in RAID 6 provide 16 TB before filesystem, metadata, spare disks and reserved space. Exclude hot spares from the member count.
  • RAID 1 here means one complete mirror across all members. RAID 01 loses a stripe set after one disk failure; RAID 10 loses a mirror only if both partners fail. For RAID 50/60, verify equal group size, parity per group and controller support. Test separate backups.
New to the terminology?
IOPS
Input/output operations completed each second.
GiB vs GB
GiB uses powers of 1,024; GB uses powers of 1,000.
Overcommit
Allocating more virtual resources than physically available.

Keep exploring

Backup Storage CalculatorStorage Unit ConverterIOPS CalculatorCapacity Growth CalculatorLearn RAID →

How calculations work and where the models stop →