What Is a File Size?

File size is a measure of the size of a computer file. Usually expressed as the number of bytes with a prefix. The actual disk space occupied by a file depends on the file system. The maximum file size of a file system depends on the number of bits that hold storage size information and the total size of the file system. For example, in the FAT32 file system, the size of a single file cannot exceed 4GiB. Some common file size units are:
1byte = 8bits
1KiB = 1,024bytes
1MiB = 1,048,576bytes
1GiB = 1,073,741,824bytes
1TiB = 1,099,511,627,776bytes