This ZFS / RAIDZ Capacity Calculator is designed to help you estimate the usable storage of your ZFS pool based on your configuration — including RAIDZ level, number of drives, drive capacity, and sector size.

Use this tool to plan your storage deployment, maximize usable capacity, and understand the overhead introduced by RAIDZ parity and ZFS slop space. Simply enter your ZFS setup details below to calculate total raw capacity, usable storage, and optional cost per TiB for budgeting purposes.

At 45Drives, we also offer ZFS education and hands-on training through webinars and guides to help you deepen your understanding of open-source storage and confidently deploy ZFS-based infrastructure.

The ZFS / RAIDZ Capacity Calculator helps you:

• Estimate total raw and usable capacity in both TiB and TB units.
• Account for RAIDZ1, RAIDZ2, or RAIDZ3 parity, ZFS slop space, and sector size overhead.
• Calculate practical usable space, based on recommended pool fill levels.
• Optionally estimate system cost per usable TiB, based on drive price.