Class 5 Calculator

Planning your data storage setup using RAID 5? Our RAID 5 Calculator helps you quickly and accurately determine the usable storage capacity, parity, and total raw storage based on the number and size of disks in your array. Whether you’re a seasoned IT professional or setting up your first NAS at home, this tool simplifies RAID 5 calculations and helps optimize your storage configuration.

What Is a RAID 5 Calculator?

RAID 5 (Redundant Array of Independent Disks Level 5) is a popular method of combining multiple hard drives for both increased storage capacity and data protection. It uses block-level striping with distributed parity, allowing one drive to fail without losing any data. However, calculating usable storage in RAID 5 can be tricky. That’s where this RAID 5 Calculator comes in.

Our web-based calculator provides:

  • Usable Storage – Space available after accounting for redundancy.
  • Parity Storage – Storage reserved for parity (fault tolerance).
  • Total Raw Storage – Combined capacity of all disks.

How to Use the RAID 5 Calculator (Step-by-Step)

Using the calculator is simple and intuitive:

  1. Enter the Number of Disks:
    Minimum of 3 disks is required for RAID 5 to function.
  2. Enter the Size of Each Disk:
    Input the storage capacity of a single disk (e.g., 500 GB or 2 TB).
  3. Select the Unit (GB or TB):
    Choose the unit of measurement based on your disks.
  4. Click “Calculate”:
    The tool will instantly display:
    • Usable Storage
    • Parity Storage
    • Total Raw Storage
  5. Reset the Form (Optional):
    Click “Reset” to start over with new values.

Practical Example

Let’s say you have 4 hard drives, each with a capacity of 2 TB.

  • Input:
    • Number of Disks: 4
    • Disk Size: 2
    • Unit: TB
  • Calculation:
    • Total Raw Storage = 4 × 2 TB = 8 TB
    • Parity Storage = 1 × 2 TB = 2 TB
    • Usable Storage = (4 – 1) × 2 TB = 6 TB

In this configuration, even if one drive fails, your data remains safe, and you retain 6 TB of usable storage.

Why Use a RAID 5 Calculator?

Calculating RAID 5 capacity manually involves understanding complex storage equations and parity logic. This tool removes the guesswork by:

  • Saving time for system administrators and home users.
  • Avoiding configuration errors in your storage planning.
  • Making capacity planning easy during server or NAS setup.
  • Clarifying trade-offs between disk count, capacity, and redundancy.

Ideal Use Cases for RAID 5

RAID 5 is best suited for:

  • File servers
  • Backup servers
  • Media servers (e.g., Plex)
  • Small to medium-sized business storage
  • Home NAS (Network Attached Storage)
  • Data archives that prioritize availability

RAID 5 balances redundancy with usable space, making it a go-to solution for many real-world applications.

FAQs: RAID 5 Calculator & Storage Planning

1. What is RAID 5?

RAID 5 is a storage method that stripes data across multiple disks with distributed parity, providing fault tolerance and good read performance.

2. Why does RAID 5 require at least 3 disks?

RAID 5 needs at least three drives to distribute both data and parity information while maintaining redundancy.

3. What happens if a disk fails in RAID 5?

Your system continues to function. Data can be rebuilt using parity once a new disk replaces the failed one.

4. How much space is lost to parity in RAID 5?

Only the capacity of one disk is reserved for parity, regardless of how many disks you use.

5. How is usable storage calculated?

Usable Storage = (Number of Disks – 1) × Disk Size

6. Does RAID 5 protect against multiple drive failures?

No. If two drives fail simultaneously, you risk total data loss. Consider RAID 6 for dual-disk fault tolerance.

7. What is parity in RAID 5?

Parity is extra data used to rebuild information from a failed disk, ensuring data protection without full duplication.

8. Can I use disks of different sizes in RAID 5?

Technically, yes—but the smallest disk’s capacity will be used as the baseline for all disks, which can waste space.

9. Is RAID 5 suitable for SSDs?

Yes, but SSDs can introduce wear-leveling and write amplification issues. Consider RAID 10 for high-performance SSD arrays.

10. What if I use 5 disks of 4 TB each?

Total: 20 TB, Parity: 4 TB, Usable: 16 TB

11. What unit should I choose—GB or TB?

Use the unit matching your disks’ labeling. Both are supported by the calculator.

12. Can I rebuild a RAID 5 array with a new disk?

Yes. Once the failed disk is replaced, the system can automatically rebuild the array using parity.

13. Is there a performance hit during rebuilds?

Yes, rebuilds can slow down system performance and may take hours or days depending on disk size and system load.

14. How secure is my data in RAID 5?

Secure from single-disk failure, but RAID is not a backup. Always use an external backup in addition to RAID.

15. Can I expand my RAID 5 array later?

Some RAID controllers support expansion, but it’s complex and risky. Always back up before attempting.

16. What happens to the data if I lose more than one disk?

Data becomes unrecoverable unless you have a backup or use advanced recovery services.

17. Is software RAID 5 reliable?

Yes, especially when managed by Linux MDADM or Windows Storage Spaces, but hardware RAID is typically faster.

18. Should I use RAID 5 for video editing?

It depends. RAID 5 offers redundancy but not the best write performance. RAID 10 may be better for intensive editing.

19. How do I maintain my RAID 5 array?

Regularly monitor SMART status, schedule health checks, and keep firmware/software up to date.

20. Does this calculator consider overhead or formatting losses?

No. The calculator assumes raw capacity. Real-world usable space may be slightly lower after formatting.

Final Thoughts

RAID 5 remains a reliable, cost-effective storage solution for environments where performance and redundancy are both important. With our RAID 5 Calculator, you can easily estimate how much usable storage you’ll get, ensuring you design your array efficiently and confidently.

Whether you’re setting up a home NAS, a small business server, or just learning how RAID works, this tool is a must-have for planning your storage architecture. Bookmark it for your next deployment!