I have a character, e.g. O, and I want to convert it to its hexadecimal encoded value. The result must be 4f.

How can I do this in Emacs 26.1?

2 Answers 2


You can simply run M-x eval-expression and type ?O. You will get the following output in the minibuffer:

79 (#o117, #x4f, ?O)
  • C-x = (what-cursor-position) works as well, it prints something like "Char: O (79, #o117, #x4f) point=146 of 146 (99%) column=0".
    – xuchunyang
    Commented Jun 20, 2019 at 23:31
  • Nice, I didn't know about ?0. A side note, by default eval-expression is bounded to M-: which make it much faster...
    – Pouya
    Commented Jun 21, 2019 at 12:47

Maybe no so elegant but should do the trick. Note I have assigned it to "C-." which might be used by other functions in your setup. Reassign as you wish:

(defun hexify()
  (setq hx (format "%x" (char-before)))
  (delete-backward-char 1)
  (insert hx))

(global-set-key (kbd "C-.") 'hexify)

Calling the function, replaces the character before the cursor with its hex. If you just want the value Arkadiusz's answer will do.

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