Recently, a question title was edited to change the date from United States format (m-d-Y) to European format (d-m-Y). The reason given was

Let's use international standards, tyvm

There are several problems with this.

  1. It was a US event, so the source dates are going to be in US format.
  2. The European format isn't the international standard. ISO 8601 (Ymd) is.
  3. The original poster used US format.

So there seems to be a couple arguments to use m-d-Y, as US events should use US date format and that was what the OP used. Or an argument that it should use the international standard. But there seems to be no argument that it should use the European standard.

In the near term, I changed it to month d, Year which is more recognizable and less ambiguous. In general, it might be a good standard to have the month name spelled out, as it reduces the ambiguity.

Can we agree on a rule so that we don't have people making edits with snarky comments? I.e. we should be referencing the Skeptics.SE standard, not allowing each user to create their own.

  • SE does Aug 19 '19. That would keep consistency. Whatever way, the European way is last on my list. – fredsbend Aug 20 '19 at 6:11
  • Incidentally, they changed it 8 years ago because of just this. meta.stackexchange.com/q/97746/212646 – fredsbend Aug 20 '19 at 6:18
  • I've requested a date shortcode. meta.stackexchange.com/q/332440/212646 – fredsbend Aug 20 '19 at 6:28
  • 1
    FWIW you did the right thing making it non-ambiguous, Let's use international standards, tyvm and then not using intl standard *sigh*. – Jamiec Aug 20 '19 at 8:27
  • It seems to me this should only be an extension to the other (dupe) question. Dates are measures of time, after all. – Sklivvz Aug 20 '19 at 8:56
  • 2
    @jamiec DMY is the interantional standard. MDY is just used by US Americans. Ref: en.wikipedia.org/wiki/Date_format_by_country – Sklivvz Aug 20 '19 at 8:57
  • 7
    To all Americans, please stop calling DMY a "European" standard, it's used by over 5 billion people. – Sklivvz Aug 20 '19 at 9:00
  • 4
    @Sklivvz I know you're familiar with ISO8601, which is the closest we have to an international format. But calling dmy "right" is no different to calling mdy "right". Its right based on where you live. Just because more people in the world use dmy it doesnt make it right. – Jamiec Aug 20 '19 at 9:36
  • @Jamiec ISO8601 is a standard, but it's a (basically) industrial standard. Speaking about grammar and actual literary usage, the de-facto standards are different. In any case the MDY choice needs to go, and the one proposed is even less used than the one I proposed... – Sklivvz Aug 20 '19 at 9:41
  • 4
    Not to mention date format has nothing whatsoever to do with the metric system. – Jamiec Aug 20 '19 at 10:30
  • 1
    The choice of what to do is already made in that accepted +26 answer: *use the metric or SI system and do edit American-style entries, except in citations". While this does not specify exactly the date format (nor should it), the idea is obviously to use an international, widely used format for legibility reasons. The question itself is already fixed. Whether it should have been edited is not up for discussion. Mandating a single format for all dates seems absurd to me. The further gist of the question is just pointing out that DMY is not an international "official" standard. – Sklivvz Aug 20 '19 at 10:50
  • 3
    But there is no metric/SI date format. So that answer doesn't begin to address this question. This question: what should we use as the standard. That question: what should we do when there are metric units. – Brythan Aug 20 '19 at 10:53
  • 1
    @Brythan that's a more reasonable question but it's not what your question is asking. BTW how is my comment unfriendly or unkind? Just because I don't like your question, it does not mean I think badly of you :-D – Sklivvz Aug 20 '19 at 10:55
  • 2
    @sklivvz The metric and SI units for time are seconds, minutes, hours, days, and years. I don't believe either system makes a judgement on how to note calendar dates. – fredsbend Aug 20 '19 at 15:47
  • 1
    It'd been my hope that xkcd would've settled this. The principal argument is consistent endianness, from which other nice properties emerge, e.g. ordering. – Nat Sep 3 '19 at 7:54

The simplest option is to just write out the date as "[month name] [day], [year]" or "[day] of [month name], [year]", rather than following a standard that is ambiguous if you don't know the standard being followed. Standards are only useful if everyone uses that standard, and the first new user who doesn't use that standard will cause even more confusion than if we hadn't agreed to a standard at all*

If you're a European, today is 19/8/2019. If you're American, it's 8/19/2019. If you follow ISO standards, it's 2019-08-19. If you follow Unix standards, it's 1566227937162. Regardless of which of those categories you fall into, as long as you know the Gregorian calendar you understand what "August 19th, 2019" or "19th of August" means.

*Anecdotally, my current work involves talking with developers in the US, Europe, and Asia, as well as having to work with servers that use a variety of timezones for their logs, and can guarantee one thing: the more people that agree to follow a standard, the more problems that are caused when someone doesn't know to follow that standard.

  • 3
    "I'll invent a standard to make these other five standards obsolete!". And now there are six standards. – Richard Aug 19 '19 at 20:08
  • Meters or feet? – fredsbend Aug 20 '19 at 6:15
  • 2
    "[month name] [day], [year]" is the worst possible format. It's not in size order. Big to small, small to large, either is fine, but "medium small, big" is daft. – dont_shog_me_bro Sep 10 '19 at 9:47
  • 2
    YYYY-MM-DD is unambiguous even if you don't know which standard is being followed (which is one of the reasons it was picked as international standard). – DevSolar Sep 24 '19 at 12:41
  • @Richard: I'm not saying we invent/follow another shorthand standard, I'm saying we ignore all of the shorthand standards entirely and just write out the month names in full. – Giter Sep 24 '19 at 14:42
  • @DevSolar: YYYY-MM-DD is unambiguous if you know the date is written to follow YYYY-MM-DD. If you're only given "2019-5-3" and no other information, then it's either May 3rd, 2019 or March 5th 2019. You could certainly assume it's following YYYY-MM-DD and you'd be right most of the time, only Kazakhstan seems to use YYYY-DD-MM, however just writing the month as a word instead of a number(2019-May-5?) gets rid of even that tiny bit of ambiguity. – Giter Sep 24 '19 at 14:51

I'll put in my two cents here, or rather, xkdc's:

ISO dates for life, sucka

I favor the iso standard for two reasons:

  1. It's ordered. Year is bigger than month is bigger than day. When ordering a list of iso formatted dates, the numbers evaluate naturally. No special regex or whatever needed. Any file naming protocol would wisely use it for this reason alone.

  2. It's entirely designed. No culture has any attachment to it, so there will be no arguments along that vein.


ISO format is the best option. Everything else will be argued over or complained about because they are not universal standards. The advantage of ISO is that it's not specific to any particular culture or region.

ISO format is also the most sensible for utility. It's ordered the same way we write numbers, with the largest on the left. It's clear and unambiguous. DDMMYY and MMDDYY can easily be confused and it's often not obvious which one is in use.

The standard format should be YYYY-MM-DD, followed by HH:MM:SS if required.

  • 1
    ISO dates are only unambiguous if you know the ISO standard, which is not a given for the non-technical audience of skeptics.SE. If you don't know the standard, there is no way of knowing whether 2019-09-10 signifies Sept 10, 2019 or Oct 9, 2019. The only standards that are truly unambiguous and clear are those that use four-digit years and month names instead of month ordinals. – Schmuddi Sep 16 '19 at 16:53
  • 1
    @Schmuddi: Where is YYYY-DD-MM a thing? To my knowledge nowhere in the world, making YYYY-MM-DD unambiguous. – DevSolar Sep 24 '19 at 12:42
  • @DevSolar: It doesn't matter if YYYY-DD-MM is used anywhere. If you come from a YYYY-MM-DD region (which seems to include large parts of Asia), you will (correctly) interpret 2019-09-10 as Sept 9, 2019. But then, this is contrary to what this answer asserts (that ISO is "not specific to any particular culture or region"). If you come from a region that has a different date standard, there is no way of knowing for sure how to interpret 2019-09-10. Unless, of course, you do know the ISO standard: then, it's unambiguous. But that's true also for any of the possible standards just as well. – Schmuddi Sep 24 '19 at 17:31
  • @DevSolar: In other words, the ambiguity does not arise from the fact that writers from region A use YYYY-MM-DD, while writers from region B use YYYY-DD-MM, and a reader of a text doesn't know if the author is from region A or B. The ambiguity arises because unless the reader knows the standard, they don't know how to interpret the date. This is different from the MM-DD-YYYY vs. DD-MM-YYYY ambiguity, but its ambiguous nevertheless. – Schmuddi Sep 24 '19 at 17:36
  • 2
    @Schmuddi: I came across an ISO date before I ever heard of it, and was able to intuitively figure out how it was intended to be read. I have yet to meet someone who wasn't. Possibly YYYY-DD-MM didn't cross my mind because, seriously, who would switch day and month around like that? Ah... blame Kazakh for screwing up a beautiful argument. :-D Anyway, no matter the rationale, I +1 ISO for being intuitive, 99.9995% unambiguous, and an international standard that doesn't hurt to raise awareness for. You don't have to agree. ;-) – DevSolar Sep 24 '19 at 17:38
  • @DevSolar: (1) I come from a DD-MM-YYYY region, and for me, the switch that some have in MM-DD-YYYY is just... not very intuitive. And still, people from MM-DD-YYYY regions believe it's a natural thing to do. (2) Was the ISO date that you encountered before you ever heard of it potentially ambiguous? (3) Don't get me wrong: I love the ISO standard for its technical properties and use it for internal representations whenever I have to store a date. However, at the output stage, I adhere to the format as defined by the user's locale setting. It's a pity that we can't do that in questions! – Schmuddi Sep 24 '19 at 18:51
  • The ISO format is standard in many parts of the world, such as Japan. The main thing is that YYYY-DD-MM is hardly used anywhere so there is very little possibility of confusion. Also it is a standard, so at least you have something to point people to. It also makes sorting easier because it's in large to small order. – dont_shog_me_bro Sep 25 '19 at 8:33

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .