Storage calculators

Free, no-signup calculators for planning hard-drive storage — capacity, cost, and backups.

RAID usable capacity calculator
How much usable storage you get from RAID 0/1/5/6/10 — and how many drives can fail before you lose data.
Cost per usable TB calculator
Your true cost per usable terabyte after parity or mirroring — the honest way to compare array builds.
3-2-1 backup planner
Size a 3-2-1 strategy — 3 copies, 2 media, 1 off-site — with room for data growth, in drives.