Cost per usable TB calculator

A drive's sticker price per TB is only the raw cost. Once parity or mirroring takes its cut, your real cost per usable terabyte is higher — this tool shows the true number for any array.

RAID usable capacity →·3-2-1 backup planner →·Cheapest drives by $/TB →

RAID level

Number of drives

Drive size (TB each)

Price per drive (USD)

Cost per usable TB

$15.00/TB

48 TB usable for $720.00 total

Cost per raw TB: $11.25/TB
Redundancy premium: +33% vs raw
Total hardware cost: $720.00
Usable capacity: 48 TB

Why this beats raw $/TB. Two builds can show the same price per raw TB but cost very differently per usable TB. A four-drive RAID 6 spends half its drives on protection; a six-drive RAID 6 spends a third — the bigger array is cheaper per usable TB even with identical drives.

Costs here are drive hardware only. Add the enclosure or NAS, and remember refurbished drives lower the price per usable TB but may shorten warranty coverage.