Storage Capacity Calculator

Estimate raw and usable capacity across multiple equal-size drives.

About the Storage Capacity Calculator

Combine equal-size drives and reserve a percentage for formatting, snapshots, free-space policy or other planned overhead.

How to use it

  1. Enter one drive capacity and select GB or TB.
  2. Enter the number of equal-size drives.
  3. Optionally reserve part of the raw capacity and calculate.

Formula

Raw capacity = drive capacity × drive count. Usable capacity = raw capacity × (1 - reserved percentage / 100).

Example

Four 2 TB drives provide 8 TB raw. Reserving 10% leaves an estimated 7.2 TB usable before other storage-layout overhead.

Notes

The calculator uses decimal base 1000. It does not model RAID parity, filesystem metadata or differences between advertised and operating-system display units.