RAID 0 Capacity Calculator
Estimate usable RAID 0 storage, mismatch waste, and theoretical speed scaling.
What this RAID 0 calculator helps you estimate
This RAID 0 calculator is designed to answer the practical questions people ask before building a striped array: How much space will I actually get? Will mixed-size drives waste capacity? and what kind of speed gain should I expect?
RAID 0 stripes data across multiple disks with no parity and no mirroring. That makes it fast and efficient in raw capacity, but it also means there is no fault tolerance. If one drive fails, the entire array is typically lost.
RAID 0 capacity formula
Equal-size drives
If all drives are the same size, the basic RAID 0 capacity formula is:
Total raw capacity = number of drives × capacity per drive
Then we subtract any filesystem overhead to estimate formatted usable space:
Usable capacity = raw capacity × (1 − overhead %)
Mixed-size drives
Most RAID implementations limit each drive to the size of the smallest disk in the set. So with mixed drives:
Total raw RAID 0 capacity ≈ number of drives × smallest drive size
Any extra space on larger drives becomes unusable in that array. This calculator shows that “mismatch waste” so you can decide whether mixing disks is worth it.
Performance expectations in RAID 0
RAID 0 can scale throughput because reads and writes are split across disks. In ideal workloads, throughput can approach a multiple of a single drive:
- 2 drives: up to roughly 2× sequential throughput
- 4 drives: up to roughly 4× sequential throughput
- Real-world results depend on controller, queue depth, file sizes, and workload type
Latency improvements are usually smaller than throughput gains, and random I/O behavior varies by device type (HDD vs SSD/NVMe).
Critical reliability warning
RAID 0 gives you zero redundancy. Reliability drops as you add more drives because the array depends on every disk being healthy. RAID 0 is often suitable for scratch data, temporary working files, gaming libraries, or workflows where backups are immediate and automatic. It is generally not suitable as the only location for irreplaceable files.
- Backups are mandatory
- Use SMART monitoring and alerts
- Keep a recovery plan before deployment
Quick examples
Example 1: 2 × 1 TB drives
Raw RAID 0 capacity is 2 TB. With a 5% overhead estimate, usable capacity is about 1.90 TB.
Example 2: 4 × 500 GB drives
Raw capacity is 2000 GB (2 TB). With 3% overhead, usable capacity is around 1940 GB.
Example 3: Mixed drives (1 TB, 1 TB, 2 TB)
Smallest drive is 1 TB, and there are 3 drives, so RAID 0 raw is 3 TB. The total physical capacity is 4 TB, so 1 TB is wasted due to mismatch (before overhead).
RAID 0 vs other RAID levels
- RAID 0: Maximum speed and full stripe performance, no fault tolerance.
- RAID 1: Mirroring for redundancy, usable capacity is roughly half.
- RAID 5: Parity-based redundancy, better capacity efficiency than RAID 1, slower writes than RAID 0.
- RAID 10: Mirror + stripe hybrid, fast and resilient, but needs more drives and higher cost per usable TB.
Best practices before you build a RAID 0 array
- Use identical drives when possible (same model, size, and firmware).
- Keep OS, controller, and firmware updated.
- Benchmark your real workload, not only synthetic tests.
- Verify your backup and restore process end-to-end.
- Consider whether a single modern NVMe drive might meet your speed needs with less complexity.
FAQ
Does RAID 0 improve gaming performance?
It can improve load times in some scenarios, but gains vary. Modern SSDs already provide strong performance; gains may be modest versus a single high-end NVMe drive.
Can I add drives later to RAID 0?
Some controllers support migration or expansion, but often it requires rebuilding the array and restoring from backup. Plan capacity up front whenever possible.
Is RAID 0 a backup?
No. RAID 0 increases performance and can combine capacity, but it does not protect data from disk failure, accidental deletion, malware, or corruption.