Hard disks, USB flash disks, and memory disks are smaller than the actual ones.

In the operating system, the capacity of the memory card or USB flash drive is less than the nominal capacity. The larger the capacity, the larger the difference.

The nominal 40 Gb storage device only shows 37 GB in the operating system; 80 GB only 74 GB; and 120gb only 112 GB. This is not because the vendor or distributor has two ways of deceiving consumers, but because the storage vendor has different computing methods on the capacity and operating system, resulting in different unit conversion relationships.
As we all know, binary is used in computers. In this way, the Capacity Calculation in the operating system is made every 1024 bytes. Every 1024 bytes is 1 kb, and every KB is 1 MB, each 1000 MB is 1 GB, while the storage vendor takes every 1000 bytes as the input. Every bytes is 1 kb, and every KB is 1 MB. Every MB is 1 GB, the difference between the two results in a reduction in storage capacity ".
Take 120 GB as an example: the vendor's Capacity Calculation Method: 120,000 GB = 120,000,000 MB = 120,000,000,000 kb = bytes, converted into the operating system calculation method: 120,000,000,000 Bytes/1024 = 117,187,500 KB/1024 = 114,440.917968 MB/1024 = 111.758708953 GB = 112 GB
Some of them need to be used for formatting or other functions and cannot be used for data storage. Therefore, the actual and nominal capacities displayed in the operating system are different. The difference between 5% and 10% is normal.