Storage · Free Interactive Tool
RAID
CALCULATOR
Choose your drive count, drive capacity, and RAID level — instantly see usable storage, parity overhead, and fault tolerance. Then request a tailored quote.
Adjust the inputs below. Results update in real time. When you’re happy with the configuration, click Get a Quote to request hardware tailored to your spec.
The reserved system capacity covers the OS partition and SWAP partition — used to install the operating system, hold system data, and store temporary files. Plan on roughly 10 GB per drive being set aside for this on each member of the array.
Available Capacity is the space free for creating volumes after the RAID is built. When you create a volume, the file system reserves additional space for metadata — ~4% on Btrfs and ~2% on ext4. Real-world usable space inside a volume is therefore slightly less than the figure above. The exact final number is reported by your NAS or server’s storage manager once the volume is provisioned.
Drive vendors label capacity in decimal terabytes (1 TB = 1012 bytes), but operating systems report storage in binary tebibytes (1 TiB = 240 bytes). A "16 TB" drive shows up as roughly 14.55 TiB to your OS. The calculator reflects that conversion, so a 4×16 TB RAID 5 array reports ~43.7 TB available rather than a flat 48.
Our engineers will source compatible drives and a NAS or server chassis matching the configuration below. Reply within one business day.
Quick reference to the RAID levels supported by this calculator. Each level trades performance, capacity, and protection differently.
Concatenates all drives into one large volume. No redundancy. Use only for non-critical bulk storage. Total usable = sum of all drives.
Splits data evenly across all drives for maximum speed. No redundancy. A single drive failure destroys the entire array. Best for scratch disks and high-throughput temporary workloads. Min 2 drives.
Writes identical copies to every drive. Survives the loss of all but one drive. Capacity = capacity of one drive. Ideal for critical operating system or boot volumes. Min 2 drives.
Distributes data and parity across all drives. Tolerates one drive failure. Usable = (N−1) × drive capacity. Common choice for general-purpose NAS and file servers. Min 3 drives.
Like RAID 5 but with two parity blocks. Tolerates two simultaneous drive failures. Usable = (N−2) × drive capacity. Recommended for arrays of 6+ large-capacity drives where rebuild times are long. Min 4 drives.
Pairs of mirrored drives that are then striped together. Tolerates one drive failure per mirrored pair. Usable = N/2 × drive capacity. Best performance and resilience for databases and virtualization. Requires an even number of drives, min 4.