RAID 5 Calculator Tool

RAID 5 is one of the most popular and reliable RAID (Redundant Array of Independent Disks) configurations, offering both data redundancy and efficient storage usage. For anyone working with servers, NAS setups, or enterprise-grade storage systems, knowing exactly how much usable space you’ll have in a RAID 5 array is critical. That’s where our RAID 5 Calculator comes in.

This tool is designed to make it fast and easy to determine the usable storage capacity, parity overhead, and redundancy level for a RAID 5 setup—all with just a couple of inputs.

🚀 What Is the RAID 5 Calculator?

The RAID 5 Calculator is a free online utility that helps users quickly assess how much usable space they’ll have after configuring a RAID 5 disk array. It also shows how much space is lost to parity (used for redundancy) and clarifies the fault tolerance level.

By inputting the total number of disks and the size of each disk (in TB), you’ll instantly receive:

  • Usable Storage – Total effective storage space.
  • Parity Overhead – The space used for storing parity data.
  • Redundancy Info – How many disks can fail without data loss.

🛠️ How To Use the RAID 5 Calculator (Step-by-Step)

  1. Enter Total Number of Disks:
    • RAID 5 requires a minimum of 3 disks, so make sure to input 3 or more.
  2. Input Disk Size (in TB):
    • Use decimal values if necessary (e.g., 1.5 TB).
    • Ensure all disks are of equal size for accurate calculations.
  3. Click “Calculate”:
    • Instantly view usable storage, parity overhead, and redundancy.
  4. Click “Reset” to Clear Values:
    • Ready to try a new configuration? The Reset button lets you start fresh.

📊 Example Use Cases

Example 1: Small Business NAS Setup

A small business is setting up a RAID 5 array using 4 disks, each with 2 TB capacity.

  • Input: 4 disks × 2 TB
  • Calculation:
    • Usable Storage = (4 – 1) × 2 = 6 TB
    • Parity Overhead = 2 TB
    • Redundancy: Tolerates 1 disk failure

Example 2: Media Server

A home media enthusiast wants to build a RAID 5 array with 6 disks, each 4 TB.

  • Input: 6 disks × 4 TB
  • Calculation:
    • Usable Storage = (6 – 1) × 4 = 20 TB
    • Parity Overhead = 4 TB
    • Redundancy: 1 disk failure tolerance

🧠 Why RAID 5 Matters

RAID 5 is a go-to configuration for balancing storage efficiency and redundancy. It’s ideal for:

  • Home NAS systems
  • Business file servers
  • Virtual machine storage
  • Media libraries

It uses one disk’s worth of space for parity across all drives, meaning you lose less space than with RAID 1, while still maintaining fault tolerance.

🔍 RAID 5 Calculator FAQs

1. What is RAID 5?
RAID 5 is a storage configuration that stripes data and parity across multiple disks, allowing one disk to fail without data loss.

2. What’s the minimum number of disks required for RAID 5?
You need at least 3 disks to configure RAID 5.

3. Can I mix different-sized disks?
Technically yes, but the smallest disk size will determine the effective capacity of each disk in the array.

4. What happens if two disks fail in RAID 5?
RAID 5 can only tolerate one disk failure. If two fail simultaneously, data loss is likely.

5. Is RAID 5 good for backups?
No. RAID is for redundancy, not backup. Always maintain off-site or cloud backups.

6. How is parity calculated in RAID 5?
Parity is distributed across all disks and uses XOR calculations to rebuild lost data from a failed drive.

7. Does the calculator account for filesystem overhead?
No. It calculates raw usable storage. Filesystem formatting (e.g., NTFS, EXT4) will slightly reduce usable space.

8. Can RAID 5 be expanded later?
Some systems support expanding RAID 5 by adding disks, but it often requires complex rebuilding or specialized hardware/software.

9. What’s better: RAID 5 or RAID 10?
RAID 10 offers better performance and fault tolerance but requires more disks. RAID 5 is more space-efficient.

10. Is SSD RAID 5 advisable?
Yes, but be cautious: write performance and SSD lifespan can be affected. RAID 10 is often better for SSDs.

11. What does the calculator mean by “parity overhead”?
This is the space used for redundancy data, equivalent to one full disk in RAID 5.

12. Does RAID 5 improve read or write speed?
RAID 5 improves read speed, but write speeds are slower due to parity calculations.

13. Can I use hot-swappable drives in RAID 5?
Yes, especially in NAS and enterprise environments. This allows drive replacement without system downtime.

14. What happens after a disk failure in RAID 5?
The system continues operating in a degraded mode. Replace the failed disk ASAP to avoid total data loss.

15. Can RAID 5 be used with external USB drives?
Technically possible, but not recommended due to performance and stability issues.

16. Will this calculator work for RAID 6 or RAID 10?
No. This tool is exclusively for RAID 5. RAID 6 uses two parity blocks, requiring different calculations.

17. Is the RAID 5 calculator mobile-friendly?
Yes, it’s designed to work on all modern browsers and devices.

18. How accurate is the calculator?
It uses the standard RAID 5 formula:
Usable = (N – 1) × Disk Size
It’s accurate for planning and capacity estimation.

19. Do I need to install software to use this tool?
No. It’s a fully web-based calculator—no downloads or installations required.

20. Is there a cost to use this RAID 5 calculator?
Absolutely not! The tool is free for all users.

✅ Final Thoughts

Whether you’re a tech enthusiast, system admin, or small business owner planning a RAID 5 storage setup, our RAID 5 Calculator makes it easy to estimate how much usable storage you’ll get—and how much space you’ll lose to parity.

Try it now and plan your storage with confidence.