Why might a newly installed 2GB hard drive show only 1.86GB of unformatted space?

When a newly installed 2GB hard drive shows only 1.86GB of unformatted space, it primarily reflects the difference between how manufacturers calculate storage capacity and how operating systems represent that capacity. Manufacturers often use the metric system for labeling disk space, where 1GB is defined as 1,000,000,000 bytes (base 10). However, computers operate using binary, meaning 1GB is calculated as 1,073,741,824 bytes (base 2).

As a result, when the operating system scans the drive, it sees the available space in binary terms. Therefore, a 2GB drive as labeled by the manufacturer actually results in less space when evaluated by the operating system due to this conversion discrepancy. This is why a 2GB drive can show approximately 1.86GB of usable space once formatted, indicating a fluctuation caused by the differing definitions of a gigabyte.

The other options do not adequately address this fundamental difference in calculation. For instance, while the presence of a swap file or diagnostic mapping could potentially affect available space, these factors are not the primary reasons for the discrepancy observed between labeled and actual usable disk space.