RAID 5 Capacity Calculator

When managing data storage systems, especially in business or server environments, understanding how much usable space you’ll actually have is critical. RAID 5 (Redundant Array of Independent Disks) is one of the most popular RAID levels due to its balance of performance, fault tolerance, and efficient storage utilization.

To help users quickly determine usable RAID 5 capacity, we've developed a free, easy-to-use RAID 5 Capacity Calculator. This tool provides instant results by requiring just two inputs: the number of drives and their individual capacity. It's designed for IT professionals, server admins, and tech enthusiasts who need accurate, real-time answers.

🧰 What Is the RAID 5 Capacity Calculator?

The RAID 5 Capacity Calculator is a web-based utility that helps you estimate how much usable storage space you will have in a RAID 5 configuration. RAID 5 uses block-level striping with distributed parity, which means that the total usable space is the size of all drives minus one. This configuration offers both improved read performance and fault tolerance—able to survive the failure of one drive.

Our calculator simplifies what would normally require manual calculations, especially when dealing with larger disk arrays. It's the perfect quick-reference tool for anyone designing or managing RAID arrays.

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

Using the calculator is straightforward and requires no technical background:

Open the Calculator Tool
Visit the RAID 5 Capacity Calculator tool on our website.
Enter the Number of Drives
Input the total number of physical drives in your planned RAID 5 setup.
⚠️ Minimum: 3 drives (RAID 5 requires at least three disks).
Enter the Drive Size
Enter the size of a single drive in GB (gigabytes).
🔄 All drives must be the same size for this tool to provide accurate results.
Click “Calculate”
The calculator will instantly display the usable RAID 5 capacity based on your inputs.
Optional: Reset the Calculator
Want to start over or try a different configuration? Click the “Reset” button to clear all fields.

✅ Example: Real-World RAID 5 Calculation

Let’s say you have 5 drives, each with a capacity of 1000 GB (1 TB).

Step-by-step:

Input 5 for Number of Drives
Input 1000 for Drive Size
Click Calculate

🔎 Result:
Usable RAID 5 Capacity: 4000 GB

📌 Why? RAID 5 uses the equivalent of one drive's capacity for parity. So:
(5 - 1) x 1000 = 4000 GB usable space

🔧 Why RAID 5? A Quick Refresher

RAID 5 is widely adopted for its balance of speed, redundancy, and cost-efficiency. Here’s why it’s so popular:

Redundancy: Can survive the failure of one disk without data loss.
Storage Efficiency: Only one disk's capacity is used for parity.
Performance: Offers better read speeds than a single disk and some write optimization.
Scalability: Easily expandable by adding more drives.

However, it’s worth noting that RAID 5 is not a substitute for backups. While it provides redundancy, it does not protect against file corruption, accidental deletions, or multiple simultaneous disk failures.

💡 Common Use Cases for RAID 5

Small to Mid-size Business Servers
Network Attached Storage (NAS) Systems
Data Warehousing and Archival
Media Production Environments
Database Storage Systems

Anywhere data needs to be both available and protected while maximizing storage efficiency, RAID 5 is often the go-to choice.

❓ Frequently Asked Questions (FAQs)

1. What is the minimum number of drives for RAID 5?

RAID 5 requires a minimum of 3 drives to function.

2. How is usable capacity in RAID 5 calculated?

It’s calculated as:
(Total Drives - 1) × Drive Size

3. Why is one drive's capacity used for parity?

RAID 5 distributes parity across all drives to allow data recovery if one drive fails.

4. Can I use different-sized drives in RAID 5?

Technically yes, but the smallest drive size will limit total capacity across all drives. Our tool assumes equal-sized drives.

5. Is the result given in GB or TB?

Our tool provides the result in GB. You can convert it by dividing by 1024 to get TB.

6. What happens if two drives fail in RAID 5?

RAID 5 can only tolerate one drive failure. If two fail, you’ll likely lose data.

7. Can I expand a RAID 5 array?

Yes, some RAID controllers and software solutions allow you to add drives to an existing array—but it can be complex and time-consuming.

8. Does RAID 5 increase performance?

Read performance improves significantly; write performance is moderately improved but parity calculation can create overhead.

9. Is RAID 5 suitable for SSDs?

RAID 5 can be used with SSDs, but RAID 10 may be better for performance-sensitive environments.

10. What’s the difference between RAID 5 and RAID 10?

RAID 5 offers better storage efficiency; RAID 10 provides better performance and redundancy but uses more drives.

11. Does the calculator consider RAID overhead?

Yes, the tool subtracts one drive’s capacity to account for parity overhead.

12. Can I use this for planning a NAS setup?

Absolutely! This tool is perfect for NAS planning with RAID 5 configurations.

13. Is this tool free to use?

Yes, the calculator is 100% free and requires no registration.

14. What if my drive size is in TB?

Simply convert TB to GB (1 TB = 1024 GB) and input the number in GB.

15. Can RAID 5 protect from data corruption?

No, it protects against disk failure but not from data corruption or accidental deletion.

16. Is RAID 5 good for home users?

It can be, especially for those with large media libraries or home labs.

17. Can I calculate RAID 6 capacity with this tool?

No, this tool is specifically for RAID 5. RAID 6 requires a different formula.

18. What if I enter less than 3 drives?

The tool will notify you that at least 3 drives are required and will not return a result.

19. Is this tool mobile-friendly?

Yes, the calculator is fully responsive and works well on all device sizes.

20. What browsers does this work with?

All modern browsers like Chrome, Firefox, Safari, and Edge support this tool.