Windows command line and Powershell do not have a default “md5sum” utility. There are many third party tools or PS scripts to do such a simple task. I prefer a pure Microsoft utility called FCIV: File Checksum Integrity Verifier. It can be downloaded from Microsoft site:

The usage is quite simple:
fciv myfile.ext calculates the MD5 checksum of the file.
fciv -sha1 myfile.ext calculates the SHA1 checksum.
fciv -both myfile.ext calculates both hashes.

A note about the installation: fciv.exe is not added to the system path, so you must do it manually. Type in the command line: setx PATH "%path%;c:\fciv" (change C:\fciv with the path of your installation)