Did you know that Windows gives two file sizes? One calls the Microsoft operating system simply “size”, the other “size on disk”. The latter is often a bit more extensive.
Different file sizes and what they mean
This distinction can be found under “Properties”, which you can access using the context menu when you right-click on the file. In the “General” tab, which is called up by default, you will find these two items of information, including the bytes. But why is Windows different here?
Windows reports two different file sizes – “size” and “size on disk”. What looks strange has its reasons.
The reason for the different size information lies in the Windows memory management. This does not refer to bytes, but to clusters. Clusters are sections that include fixed, predefined sizes. With hard disks or partitions that are partitioned in the usual NTFS format, the size of a cluster is usually 4096 bytes. At the same time, a file always occupies an entire cluster. If the file size exceeds 4096 bytes, for example 4099 bytes, the individual cluster is not sufficient. The result: The “size on data carrier” then increases to a total of two clusters and thus to 8192 bytes.
The memory management under Windows does not take place in individual bytes as with hard disks, but in clusters with fixed sizes.
With the NTFS file system, there are two other peculiarities that can provide different file sizes: Particularly small files that require a maximum of 700 bytes of memory do not take up any hard disk space, as this data is saved by the system directly in the associated directory entry. Finally, there are the options for compressing folders and “sparse files”, in which empty sections of the file do not require storage space. These two options can also mean that the “Size on disk” is smaller than the specification under “Size”.
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