RAID Storage Calculator
Usable storage capacity for common RAID levels.
Reviewed by James Whitfield · How we check our maths
Your values
ⓘ Live results
Results
- 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.
The formula
Varies by RAID level (0, 1, 5, 6, 10)
Worked example
Worked example
Using the values the calculator loads with.
Inputs
- Number of drives6
- Drive size4 TB
- RAID levelRAID 5
Result
- Usable capacity20 TB
- Raw capacity24 TB
- Fault toleranceSurvives 1 drive failure
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.
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.
About this calculator
- Built and reviewed by James Whitfield · How we build and test calculators
- Report an error