File size and footprint size (with byte to KB,MB formula)

A lot of people have been confused, "size" and "footprint (size on disk)" In a file or folder property usually do not match each other. The value of size represents the number of bytes in the actual size of the file, while the space-occupying value table file occupies the size of the hard disk space.

This difference comes from the way the file system stores files on the drive. To reduce the number of addresses used, the file system treats a certain number of bytes as clusters. Depending on the file system, the common cluster size can range from 2KB to 32KB. A file written to disk needs to occupy several unconnected clusters regardless of the actual size of the file. Therefore, a 1KB file, saved in a cluster size of 2KB file system will occupy 2KB, but saved in a cluster size of 32KB file system, it will occupy 32KB. In other words, a 33KB file will occupy 17 2KB clusters (34KB) or 2 32KB clusters (64KB).

Based on the above discussion, you will expect the size of the space to be larger than the actual size, but the extra portion will not exceed the size of one cluster. This difference can be greater when viewing a folder with many files, because the space wasted by each individual file is added to the folder.

To put it simply,"size" is the actual number of bytes in the file, and "space" is the number of bytes occupied on disk.

Example:

Conversion program

File size and footprint size (with byte to KB,MB formula)