When files are very small then we can compare them manually and find out if the two files are identical. Windows provides tools such as the fc command using which we can compare two files either in text mode or in the binary mode. But when files are huge, and you don’t want to download these files over and over again for comparison, then it is better to use file checksums or hashes.
File hashes generated using a particular algorithm are unique for a file. When the file is modified even a single byte, the file hash will be different. This is why we can safely find out whether the file on a server is different from the file on our local storage media.
We can use a free tool called fHash for calculating and verifying the file hashes in Windows. It is basically a portable software by can also be added to the right-click context-menu. We can launch it and then drag-n-drop the files on its window, it will quickly generate four different types of hashes – MD5, CRC32, SHA1 and SHA256.
If you want to verify the file hashes, then you have to first open a file and let it calculate all the hashes as usual. After this you can click on the “Verify” button and copy/paste the file hash that you have found from the website from where you downloaded the original file. It will quickly tell you if there is a match.
fHash is very fast and we could calculate SHS256 hashes of various ISO images with it in a matter of seconds. For the Windows 11 ESD image (over 6 GB) it took nearly 4 minutes. It uses a very very small amount of the system resources and is ideal for casual calculation and comparison of file hashes on a Windows PC.
You can download fHash from https://sourceforge.net/projects/fhash/.