awhile

Awhile calculates the difference between two moments in time and then
displays it in one of a few available formats. When a second moment is not
given, it's assumed to be "now".

You can customize how you want to display a time difference: long or short,
exact or fuzzy, which units to use, etc.

You can also directly convert seconds to one of these formats.

And you can convert these formatted outputs back to seconds, or to one of
the other formats.

See the README for more information

Open it easily with:
  (find-file-read-only "README.org")   <--- C-x C-e here¹

or from any buffer:
  M-x awhile-see-readme

or read it online:
  <https://flandrew.srht.site/listful/sw-emacs-awhile.html>

¹ or the key that ‘eval-last-sexp’ is bound to, if not C-x C-e.