FHash is an easy-to-use application for quickly calculating various file hashes (MD5, SHA1, SHA256, CRC32).
There's no installation required, no hassles or issues of any kind. Just select one or more files, drag and drop them onto the program, and it calculates and displays their various details: file name, size, modified date, version, MD5, SHA1, SHA256, CRC32.
Clicking "Copy" sends all this information to the clipboard, or you're able to select and copy just a part of it.
Dragging and dropping more files adds their information to the end of the current list, or you can click "Clear" to delete everything and start again.
If this isn't quite convenient enough, an "Add to Context Menu" option enables you to call up fHash from Explorer's right click menu. (Okay, that's not quite so "portable", but when you've finished the program can remove its entry with a click.)
Please note, while the Windows version is free, the Mac edition is priced at $0.99.
Hash calculator don't get any simpler than this.