RAID Calculator
Find usable storage capacity for a RAID array.
RAID levels trade capacity for redundancy and speed.
How the Math Works
RAID levels determine how storage capacity is allocated for redundancy and performance. For example, RAID 0 stripes data across all drives for maximum capacity but no redundancy, while RAID 1 mirrors data, halving the total capacity. RAID 5 uses one drive's worth of space for parity, giving (n-1)/n of total capacity, and RAID 6 uses two drives for parity. The formula varies: RAID 10 combines mirroring and striping, yielding 50% of total capacity. The calculator applies these ratios based on the selected RAID level and number of drives.
Practical Applications
To use the RAID Calculator, input the number of drives and their individual capacity, then select your desired RAID level. The tool instantly computes usable storage by applying the level-specific formula (e.g., RAID 5: (Total Drives - 1) × Drive Capacity). This helps in planning storage budgets for servers, NAS devices, or workstations, ensuring you balance cost, redundancy, and performance needs before purchasing hardware.
Day-to-Day Use
Whether managing a home media server or enterprise data center, this calculator prevents costly miscalculations. It clarifies trade-offs—like how RAID 6 sacrifices capacity for dual-disk failure protection—helping you choose the right setup for backups, video editing, or cloud storage. Avoid overbuying drives or underestimating risks, making informed decisions that save money and protect critical data in everyday tech use.
Worked example
Four 4 TB disks in RAID 5 give 12 TB usable.
FAQ
Which level is safest?
RAID 6 survives two disk failures; RAID 0 has no redundancy.