RAID Storage Calculator
Usable storage capacity for common RAID levels.
Enter your values
Enter the number of drives you are working with.
Enter the drive size in TB.
Choose one of: RAID 0 (striping), RAID 1 (mirroring), RAID 5, RAID 6, RAID 10.
Results update instantly as you type — no submit needed. Your values are remembered on this device, and the shareable link reopens the calculator with exactly these numbers.
- Usable capacity
- 20 TB
- Raw capacity
- 24 TB
- Fault tolerance
- Survives 1 drive failure
Quick answer
Usable capacity depends on RAID level, drive count and individual drive size.
Varies by RAID level (0, 1, 5, 6, 10)
At a glance
| What it does | Usable storage capacity for common RAID levels. |
|---|---|
| Category | Technology |
| Inputs needed | Number of drives, Drive size, RAID level |
| Main output | Usable capacity |
| Formula | Varies by RAID level (0, 1, 5, 6, 10) |
| Cost | Free — no sign-up, no download |
How to use the RAID Storage Calculator
- 1Enter the number of drives and the capacity of each drive.
- 2Choose your RAID level.
- 3Read the usable capacity and how many drive failures the array can tolerate.
Inputs explained
- Number of drives
- Enter the number of drives you are working with.
- Drive size(TB)
- Enter the drive size in TB.
- RAID level
- Choose one of: RAID 0 (striping), RAID 1 (mirroring), RAID 5, RAID 6, RAID 10.
Worked example
Using the values the calculator loads with:
Inputs
- Number of drives6
- Drive size4 TB
- RAID levelRAID 5
Results
- Usable capacity20 TB
- Raw capacity24 TB
- Fault toleranceSurvives 1 drive failure
Frequently asked questions
Which RAID level should I use?
RAID 5/6 balance capacity and redundancy for general storage; RAID 10 offers better performance and rebuild safety at higher cost.
Is RAID a backup?
No — RAID protects against drive failure, not accidental deletion, corruption or theft; always keep separate backups.
What do I need to enter into the RAID Storage Calculator?
Just 3 values: number of drives, drive size, raid level. Every field starts with a realistic example, so you can change one number at a time and watch the result update instantly.
How does the RAID Storage Calculator work out the answer?
Usable capacity depends on RAID level, drive count and individual drive size. It applies the formula Varies by RAID level (0, 1, 5, 6, 10) and shows the working so you can check each step by hand.
Is the RAID Storage Calculator free, and do I need an account?
It is completely free with no sign-up, no download and no usage limit. Everything is calculated in your browser, so the numbers you type never leave your device.
Results are estimates for general information. For medical, legal, structural or financial decisions, confirm with a qualified professional.