Disk manufactors(HDD, SSD, SD cards, xD cards, flashes, etc) use a base-10 numeral system, and Windows use a binary system. For example disk manufactors use 1 kilobyte - 1000 byte; 1 megabyte - 1000 kilobyte; 1 gigabyte - 1000 megabyte, etc while operating system, ram, cpu, ppu, gpu manufactors use 1 kilobyte - 1024 byte; 1 megabyte - 1024 kilobyte; 1 gigabyte - 1024 megabyte; 1 terabyte - 1024 gigabytes; 1 petabyte - 1024 terabytes, etc. 500 Base-10 GB is approximately 465.66 Windows GB. Thats why it shows 465.66 gigabytes