The size of a file is the amount of space it takes up on your hard drive. The File Size is measured in bytes as opposed to bits. One byte consists of 8 bits. The value is thus given out in bytes, kilobytes (KB), megabytes (MB), gigabytes (GB) and so on. One megabyte is 1024 kilobytes, one kilobyte is 1024 bytes, etc.
The display of the File Size might wary by a few bytes depending on the hard drive it is saved on. Some files might take up a little more space on an external drive like a USB stick as compared to on the hard drive. Usually, it is displayed in the most economic way. Meaning that, in many cases, a long number like 55366 bytes will be shown as 54 KB. However, both ways of displaying File Size information is used.
The File Size plays a crucial role when it comes to calculating and saving space on your hard drive, sending files or uploading them to the internet.