The date format is usually written as mm/dd/yy and sometimes the month written out followed by the day followed by a comma and the year. My question is: is it academically acceptable to write the date in mm.dd.yy format? I like the . . . format better than the / / / format, which is why I ask the question.

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    There are only a handful of countries that use the MDY format. Unless whatever you're writing is intended for the US only and not for an international audience, you should better use the much more common DMY (with whatever separator you like) or the Y-M-D format (ISO 8601).
    – Niko
    Nov 2, 2015 at 19:15
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    This seems entirely language dependent. Dates are not usually "written as mm/dd/yy" in academia, but in American English. If you write in a different language, you will have to follow the conventions of that language, whether they are "mm.dd.yy" (not sure which language uses this format), or anything else. Nov 2, 2015 at 19:15
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    @Llopis: Well, being German myself, I have to nitpick here ;) At least in Germany, strictly speaking, a "ddmmyy" format is used, where "dd" and "mm" happen to be ordinal numbers, which are indicated by a trailing dot in German. The dot is not a delimiter in the date format; it is a part of the "dd" and "mm" components (as becomes apparent when skipping the year - skipping the year in 11/15/2013 yields 11/15, but skipping the year in 15.11.2013 yields 15.11., not 15.11). Nov 2, 2015 at 20:14
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    What does "academically acceptable" even mean? Nov 2, 2015 at 23:27
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    At a minimum, "academically acceptable" would imply that a competent reader knows without doubt what the author meant. If you write for example "05.07.15" then I would guess that it might be a German date in July, but used within English text I would then think that this guess isn't very justified and I have actually no idea whether this is a date in May or July. So not academically acceptable. I would then also be left wondering what else in this text I cannot trust.
    – gnasher729
    Nov 2, 2015 at 23:41

4 Answers 4


The International Standard ISO 8601 is YYYY-MM-DD. See Wikipedia and A summary of the international standard date and time notation.

Sadly this is not used by everyone as can be seen in this article about date formats per country:

  • The most popular order is day-month-year (Little-Endian, cyan in the image), used by about 57% of the world population.
  • Next is year-month-day (Big-Endian, yellow), used by about 29%.
  • Then month-day-year (Middle-Endian, magenta), used by about 6%.
  • The remaining 8% use a mix of the above.

date format per country

But, in the end the most important is the standards used in your university or the conference or journal you are sending your papers to.

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    Obligatory xkcd that's probably the only reason anyone has ever heard of ISO 8601.
    – user4512
    Nov 2, 2015 at 22:23
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    Obligatory xkcd retort against ISO 8601 (I'm just kidding, for what it's worth)
    – tonysdg
    Nov 2, 2015 at 23:37
  • @ChrisWhite: Eh no many of us are actually competent and knowledgeable, as well as being comic fans :) Nov 3, 2015 at 0:51

As a millennium programmer the only way to remove ambiguity I've found is that you spell out the month and use 4 numbers for the year:

December 4th 2015

4 December 2015

2015 December 4

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    This is the definitive answer in my view. The point of writing is to convey meaning. If the meaning is unclear because different people may interpret things differently, then you made a mistake in your choice. So, rather than trying to ask what is "acceptable" or "typical", the question you need to ask is "How do I unambiguously convey what I want to say to the reader?". Nov 3, 2015 at 1:02

If someone else has authority over your format, for example your advisor or the publisher of the journal you're writing for, then follow that someone's format requirements. If there's nobody with such authority, or if the person with authority doesn't care about the format, then use whatever format you like (but make sure you use it consistently).


I would agree with the recommendation to use ISO8601. Not only is it an recognized international standard, it's logical, it removes ambiguity, and by using it, you'll help to spread awareness. The sooner all of the other formats for date and time die off, the better for everyone.

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    I upvoted this because I agree with promoting the ISO format, but I still think your expectation that "other format for date and time die off" is unrealistic. Note that it is not because people are averse to change and the usual excuses, but that various other formats for date and time are closely linked to the way date and time are spoken in the respective languages when read out loud. Taking the example of German dates mentioned above, German speakers will not just write "3.4.11" because that's the convention for writing dates, "3.4.11" is literally read out "dritter vierter elf" ... Nov 3, 2015 at 0:06
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    ... (in English: "third fourth eleven"), which is simply how a date is pronounced in German. Even when writing "2011-04-03", the date will still be pronounced "dritter vierter [zweitausend]elf" and not "zweitausendelf null-vier null-drei" ("two thousand eleven zero-four zero-three"), because that's not how a date is indicated in German. Hence, I do not expect other formats for date and time to die off, at least not when used in a sentence. Nov 3, 2015 at 0:08
  • I would agree that it is unlikely that other spoken and "long format" written dates would die off. Hopefully though if ISO8601 gains enough traction it would become the norm in technical writing. It's such a simple way to end the ambiguity. Nov 5, 2015 at 15:59

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