Gigabytes missing from unit

Even if there are Gigabytes missing from the storage devices that I purchased, there is nothing wrong with your device.
The issue is how computers measure drive space, as compared to how hard drive manufacturers measure drive space.

Computer memory is addressed in base 2, due to its design, so memory size is always a power of two. It is thus convenient to measure in binary units.
Other computer measurements, like storage hardware size, data transfer rates, clock speeds, operations per second, and so on do not have an inherent base, and are usually measured in decimal units.

Consumers who are unaware of varying meanings of the abbreviations often feel shortchanged when they discover the difference, and claim that manufacturers of drives and data transfer devices are using the decimal measurements in an intentionally misleading way to inflate their numbers, though these measurements are the norm in all fields other than computer memory and storage.

For instance, if a hard drive is said by a vendor to store 140 GB of data, the disk can store 140000000000 bytes.
Generally, operating systems allocate and report disk and files sizes in binary units, and present them using abbreviations (e.g GB, MB, KB) also used by the decimal system, so this drive would be reported as "130 GB" (actually 130.38 GiB).