The format-time-string function takes a time argument like '(21761 64499 350937 0) and a format string like "%y-%m-%d %a %H:%M" and returns something like "15-03-12 Thu 16:49".

What is the inverse function, which takes "15-03-12 Thu 16:49" and "%y-%m-%d %a %H:%M", and returns '(21761 64499 350937 0)?

I am trying to parse times out of a website so as to convert them into org-mode timestamps, but I'm having trouble finding the right function in the emacs documentation.

Edit I'm promoting this from my comment to erikstoke's answer. parse-time-string and org-parse-time-string are insufficient because while they parse many standard time strings, they do not allow for specified formats. Both functions are rather incomprehensive. In particular, they lack ISO8601 support.

2 Answers 2


parse-time-string parses "standard" time strings, as does org-parse-time-string. The documentation claims the latter will be faster. Neither gives a way to specify the format of the string.

There is also an undocumented function parse-iso8601-time-string that parses ISO8601 into something. It isn't clear to me what the output is supposed to be.

  • Indeed, I checked those out. They even return "Invalid time specification" when fed ISO8601, which is why I'm still looking. Mar 12, 2015 at 21:06
  • (parse-time-string (current-time-string)) works here.
    – wasamasa
    Mar 12, 2015 at 21:17
  • There is a function that claims to do this, but I don't see what the output is supposed to mean. I edited it into my answer.
    – erikstokes
    Mar 12, 2015 at 21:22

I had a similar situation but couldn't find anything working out of the box. But since org-time-stamp handles all kinds of formats, I figured the code was there. The function below will insert an org time stamp from a provided time string. I haven't tested it for all kinds of times, but for "15-03-12 Thu 16:49" it will give "[2015-03-12 tor 16:49]". ("tor" is Thursday in my locale).

So this answer is not fully matching the question, since you don't have a way of providing the format string, but hopefully it will work out anyway. It should understand all formats that org-time-stamp handles.

(defun jk-org-insert-time-stamp (time-string)
  (interactive "sTime: ")
  (let ((default-time (apply 'encode-time (decode-time))))
     (apply 'encode-time (org-read-date-analyze time-string default-time default-time)) t t)))
  • this does not answer the question. The question was, how can I parse a string with a specified format? This function inserts a timestring with a specified format.
    – Cheeso
    Nov 21, 2017 at 20:10

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