When viewing your storage size on a system, you might notice that the usable space appears smaller than the advertised size. This discrepancy arises due to differences in how storage manufacturers and operating systems measure storage units. Below, we break down why these differences occur and what you can expect.

Storage manufacturers use the decimal system to measure storage capacity. In this system:

On the other hand, operating systems and most IT systems rely on the binary system, which defines storage units as follows:

The binary system results in larger byte values for the same unit names, which leads to different total storage calculations.

Since manufacturers use the smaller base values from the decimal system, the storage they advertise appears larger than what your system, using the binary system, calculates. For instance:

This difference is not due to data corruption, caching problems, or hardware issues—it is simply a result of the different unit standards.

Here are some approximate examples to illustrate the difference between advertised and reported sizes:

These differences apply across all storage systems, including external hard drives, SSDs, and cloud-based solutions like seedboxes.

Discrepancies between advertised and reported storage sizes are expected and arise from the use of different storage measurement standards. Being aware of these can help set realistic expectations about your system's usable storage capacity.