A file's size refers to how much space it consumes on the hard disk. The size of a file is measured in Bytes, in contrast to bits. Certain files can take up more space on an external drive, such as a USB stick, as opposed to the drive. Most of the time, they are presented in the most economical method. That is, in many instances, a large number, such as 55366 bytes, will appear with the format 54 KB. But both methods of showing File Size information are used. The Size of the File is a key factor in the calculation of space and saving it within your disk.