RAID usable capacity calculator
Estimate usable capacity after reserving parity drives.
How to use the RAID usable capacity calculator
What does the RAID usable capacity calculator do?
Estimate usable capacity after reserving parity drives; It applies this page-specific rule: usable capacity equals total drives minus parity drives, multiplied by the smallest drive size.
Which inputs does this calculator use?
To estimate usable capacity after reserving parity drives, enter Drive count, Drive size (TB), Parity drives; keep every value in the same example; select Calculate when the values are ready; Start with a familiar case covered by this rule - The model covers simple equal-sized parity layouts such as RAID 5 or RAID 6 capacity planning - so the expected result can confirm the settings.
How should the calculator result be read?
For a result intended to estimate usable capacity after reserving parity drives, the model covers simple equal-sized parity layouts such as RAID 5 or RAID 6 capacity planning; read parity drives together with the original drive count rather than as an isolated answer, and confirm that its units or structure match the intended use.
What calculation does this use?
When the goal is to estimate usable capacity after reserving parity drives, usable capacity equals total drives minus parity drives, multiplied by the smallest drive size.
Why might a real result differ?
When using the page to estimate usable capacity after reserving parity drives, formatting, hot spares, metadata, mixed drive sizes, vendor definitions, and rebuild safety are not included.
Limits and accuracy
When using this calculator to estimate usable capacity after reserving parity drives, formatting, hot spares, metadata, mixed drive sizes, vendor definitions, and rebuild safety are not included; the result is an estimate unless every source value is known; codecs, metadata, overhead, and variable bitrates can change an actual file; keep drive count until the output has been checked in its intended destination.
How raid usable capacity calculator works
Usable capacity equals total drives minus parity drives, multiplied by the smallest drive size.
The model covers simple equal-sized parity layouts such as RAID 5 or RAID 6 capacity planning.
Formatting, hot spares, metadata, mixed drive sizes, vendor definitions, and rebuild safety are not included.
Frequently asked questions
What calculation does this use?
Usable capacity equals total drives minus parity drives, multiplied by the smallest drive size.
Why might a real result differ?
Formatting, hot spares, metadata, mixed drive sizes, vendor definitions, and rebuild safety are not included.
Are these values uploaded?
No. The calculation runs in this browser tab.