To get the SHA-256 hash value for a file, you can use this app which runs directly in the web browser:
All you need to use this tool is a modern web browser like Google Chrome or Firefox. (The hash is computed in the browser, no upload is necessary)
When you have opened this page, you can pick the file by dragging it from the windows explorer onto the area labeled
Drop file here, or click to browse.
Depending on the size of the file, it might take several seconds to compute the hash.