RAID Calculator
Choose your RAID type and drive size to see how much storage space you can actually use.
Enter the size of one drive, or pick a common size below.
This result needs attention
The result is available, but this RAID setup has an important limitation.
Your estimated RAID capacity
Here is an estimate of your total space, usable space, and protection overhead.
- Total drive space
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- Usable space
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- Space used for protection
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- Efficiency
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- Fault tolerance
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This setup needs to be adjusted
A few settings need to be fixed before we can calculate the result.
How to Use This RAID Calculator
Use this RAID calculator to estimate how much storage space you can actually use in a RAID setup. Choose your RAID type, enter the number of drives, and add the size of each drive. The calculator will show your total space, usable space, protection overhead, and fault tolerance.
Step 1. Choose Your RAID Type
Select the RAID setup you want to check, such as RAID 0, RAID 1, RAID 5, RAID 6, RAID 10, RAID 50, RAID 60, or JBOD. Different RAID types offer different balances of speed, redundancy, and usable storage space.
Step 2. Enter the Number of Drives
Type in how many disks are included in the array. This affects both your total available space and the level of protection your RAID can provide.
Step 3. Enter the Size of Each Drive
Enter the size of one drive in terabytes. If all drives are the same size, you only need to enter it once. You can also use the quick size buttons for common drive sizes.
Step 4. Review the Result
Once the setup is valid, the calculator shows your estimated RAID capacity right away. If there is a configuration issue or an important limitation, you will also see a message explaining what needs attention.
What the Results Mean
Total drive space
This is the full raw capacity of all drives combined before RAID protection is taken into account.
Usable space
This is the estimated storage space you can actually use for your files after mirroring, parity, or other protection is reserved.
Space used for protection
This is the part of your storage that is used for redundancy, parity, or spare capacity rather than for your own data.
Efficiency
This shows how much of your total drive space remains available for storage after RAID overhead is applied.
Fault tolerance
This tells you how many drive failures a RAID setup may survive before data loss becomes likely. The exact result depends on the RAID type and layout.
RAID Types Explained
JBOD
Minimum drives: 1. Best when you want to use all available space and do not need redundancy. The drawback is simple: if the drive fails, your data is at risk.
RAID 0
Minimum drives: 2. Best for speed and full capacity. It offers no fault tolerance, so a single failed drive can make the array unavailable.
RAID 1
Minimum drives: 2. Best for simple mirroring and straightforward protection. The main trade-off is that only about half of the total drive space is usable.
RAID 5
Minimum drives: 3. Best for balancing usable space and protection. It can survive one drive failure, but parity overhead reduces available capacity.
RAID 6
Minimum drives: 4. Best for larger arrays where stronger protection matters. It reserves more space for redundancy than RAID 5.
RAID 10
Minimum drives: 4. Best for strong performance with redundancy. The trade-off is higher storage overhead because mirroring uses a large part of total capacity.
RAID 50
Minimum drives: 6. Best for larger grouped arrays that need a balance of speed, capacity, and protection. It requires correct group sizing to work as expected.
RAID 60
Minimum drives: 8. Best for grouped arrays where higher fault tolerance is more important than maximum capacity. It has more overhead than RAID 50.
Common Examples
Example 1. 4 x 2 TB in RAID 5
Total drive space is 8 TB. Usable space is about 6 TB because the equivalent of one drive is used for parity.
Example 2. 4 x 4 TB in RAID 6
Total drive space is 16 TB. Usable space is about 8 TB because two-drive parity is reserved for protection.
Example 3. 6 x 8 TB in RAID 10
Total drive space is 48 TB. Usable space is about 24 TB because half of the total capacity is used for mirrored protection.
Example 4. 8 x 2 TB in RAID 60
Total drive space is 16 TB. Usable space depends on the group size, but dual-parity overhead will significantly reduce available space.
Example 5. 1 x 4 TB in JBOD
Total drive space and usable space are the same at 4 TB, but there is no redundancy.
Which RAID Level Should You Choose?
Choose RAID 0 if speed matters most and you do not need fault tolerance.
Choose RAID 1 if you want a simple way to mirror data across drives.
Choose RAID 5 if you want a practical balance between usable space and protection.
Choose RAID 6 if you use a larger array and want better protection against multiple drive failures.
Choose RAID 10 if you want strong performance with redundancy and can accept higher overhead.
What This Calculator Does Not Show
- Actual usable size may vary slightly depending on formatting, controller behavior, and vendor implementation.
- This calculator estimates storage capacity. It does not predict whether data recovery will succeed after a failure.
- Some controller-specific RAID layouts may behave differently from the standard models used here.
FAQ
What is usable RAID capacity?
Usable RAID capacity is the amount of storage space you can actually use after RAID protection, parity, or mirroring is taken into account.
Why is usable space smaller than total drive space?
Many RAID types reserve part of the total space for redundancy. That extra space helps protect your data if a drive fails.
How many drives do I need for RAID 5?
RAID 5 requires at least 3 drives.
What is the minimum for RAID 6?
RAID 6 requires at least 4 drives.
Is RAID 10 better than RAID 5?
It depends on your goal. RAID 10 usually offers better performance and strong redundancy, while RAID 5 usually gives you more usable storage space.
Does RAID protect against accidental deletion?
No. RAID can help with hardware failure, but it does not protect against accidental deletion, corruption, malware, or formatting mistakes.
Can this calculator help me recover lost files?
No. This calculator estimates RAID capacity. It does not recover data or analyze a failed array.
What should I do if my RAID has failed?
Stop using the array, avoid rebuilding it until you understand the problem, and use a trusted RAID recovery solution if your data is important.
Need to Recover Data from a Failed RAID?
DiskInternals RAID Recovery can help you recover documents, photos, videos, databases, and other files from damaged or inaccessible RAID arrays.
- Supports RAID 0, RAID 1, RAID 5, RAID 6, RAID 10, RAID 50, RAID 60, and JBOD.
- Lets you preview recoverable files before purchase.
- Designed for step-by-step recovery from many common RAID failure scenarios.
Use the RAID RECOVERY FREE DOWNLOAD button above to get started. If you need help, you can also contact Technical Support.