Japan is on its own wavelength.

YYYY-MM-DD is the only acceptable date format, as commanded by ISO 8601.

"There shall be no other date formats before ISO8601. Remember this format and keep it as the system default"
Largest to smallest unit of time. It just makes sense.
Sorting by date would be so much better with yyyymmdd .
ISO 8601, while great, has too many formats. May I introduce RFC 3339 instead?
https://ijmacd.github.io/rfc3339-iso8601/
- That is what I love so much about standards: there are so many to choose from.
- YES! I wish more people knew about RFC 3339. While I'm all for ISO 1601, it's a bit too loose in its requirements at times, and people often end up surprised that it's just not the format they picked...
- Huh, I've never noticed how much bloat was in ISO 8601. I think when most people refer to it, we're specifically referring to the date (optionally with time) format that is shared with RFC 3339, namely 2023-11-22T20:00:18-05:00 (etc). And perhaps some fuzziness for what separates date and time.
If you have years of files named similarly with the date, you will love the ISO standard and how it keeps things sorted and easy to read.
- I have autohotkey configured to insert the current date in ISO 8601 format into my filenames on keyboard shortcut for just this reason. So organized. So pure.
Glad I can count my own country, Lithuania, among the enlightened.
EDIT: Source of the picture: https://en.m.wikipedia.org/wiki/File:Date_format_by_country_NEW.svg
- Which color is which?
- Canada threw up their hands and said, "Fuck it, I don't care, use whatever date format you like."
- where's that? somewhere in africa?
  /s because apparently it's not implied
YYYY-MM-DD:HH:MM:SS
- Funny thing, in ISO 8601 date isn't separated by colon. The format is "YYYY-MM-DDTHH:MM:SS+hh:mm". Date is separated by "-", time is separated by ":", date and time are separated by "T" (which is the bit that a lot of people miss). Time zone indicator can also be just "Z" for UTC. Many of these can be omitted if dealing with lesser precision (e.g. HH:MM is a valid timestamp, YYYY-MM is a valid datestamp if referring to just a month). (OK so apparently if you really want to split hairs, timestamps are supposed to be THH:MM etc. Now that's a thing I've never seen anyone use.) Separators can also be omitted though that's apparently not recommended if quick human legibility is of concern. There's also YYYY-Wxx for week numbers.
- YYYY-MM-DD:HH:MM:SS+TZ
- YYYY-MM-DDTHH:MM:SS.SSSSSSSSSZ
- This, but all run together.
  I write files/reports to disk a lot from scripts, so that's my preferred format.
Except the information is given least to most important, making verbal abbreviation difficult. Works great for file names though.
- There's this really cool shorthand where you drop the year because it seldom changes. It's called MM-DD
For file names, absolutely.
When I’m asking what date it is I typically know the current year.
- Well la-tee-dah, look at mister not-shitfaced-every-day here, bragging like a big man
Is that why the military uses that format?
- In a GMP laboratory it's 22NOV2023 no ambiguity.
- Yep, you can easily sort it just because of the ordering. It's a full standard
The truth. Amen
It's alphabetically sortable too. Name backups like this.

DD/MM/YY and YY/MM/DD are the only acceptable ones IMO. Throwing a DD in between YY and MM is just weird since days move by faster so they should be at one of the ends and since YY moves the slowest it should be on the other end.

I'm not kidding when I ask: are there really a lot of people using MM/DD/YYYY??
- Almost 350 million of us morons down south of you.
- I think most Americans do. Or at least it was taught that way in school when I was growing up. Maybe it’s because of the way we speak dates, like “October 23rd” or “May 9th, 2005”.
  Regardless, the only true way to write dates is YYYY-MM-DD.
- Pretty much every American I've ever met. Dates on drivers license, bank info, etc - all in MM/DD/YYYY ... or even just MM/DD/YY
  I regularly confuse people with YYYY-MM-DD
If you use DD/MM/YYYY, dumb sorting algorithms will put all of the 1sts of every month together, all of the 2nds of every month together, etc. That doesn't seem very useful unless you're trying to identify monthly trends, which is fundamentally flawed as things like the number of days in the month or which day of the week a date falls on can significantly disrupt those trends.
With MM/DD/YY, the only issue is multiple years being grouped together. Which may be what you want, especially if the dates are indicating cumulative totals. Depending on the data structure, years are often sorted out separately anyways.
YYYY/MM/DD is definitely the best for sorting. However, the year is often the least important piece in data analysis. Because often the dataset is looking at either "this year" or "the last 12 months". So the user's eyes need to just ignore the first 5 characters, which is not very efficient.
If you're using a tool that knows days vs months vs years that can help, but you can run into compatibility issues when trying to move things around.
The ugly truth no one wants to admit on these conversations is that these formats are tools. Some are better suited to certain jobs than others.
I grew up with DD.MM.YYYY. But I think, MM/DD makes sense in everyday usage. You don’t often need to specify dates with year accuracy. “Jane’s prom is on 7th September” – it’s obvious which year is meant. Then it’s sensible to start with the larger unit, MM, instead of DD.
Even in writing you see that the year is always given like an afterthought: “7th September**,** 2023“.
The only reason they place month as first is because it is fits how dates are read in English, but that's not a good reason to keep that format.
- It's how it is read in English (simplified) aka american english. Brittish english doesn't do this nonsense, the talk in the correct format (first of january etc.).
  (I'm sorry if i made some mistakes, english is my second language)
- You only think it fits with how it's read in English because that's how you grew up saying it so it sounds natural to you. Your experience is not universal, and is in fact, a minority.
I hope you mean YYYY, not just YY
Should just burn it all down and do. MM/YY/DD
Japan is YYYY-MM-DD, but when we talk about dates where a year is unneeded, we just cut it off which leaves it in the US standard format of MM-DD, much to the annoyance of non-US foreigners living here.

ISO 8601 format is the best (YYYY-MM-DD).

Came here to say this. I try to name all my docs in the YYYY-MM-DD-descriptive-name.ext format.
- I can see some advantages of that.
  I'm American though, so YYYY-DD-MM is the best I can do.
I like that for files, but not for written documents. When I label things I try to use the most intuitive/least confusing way I can think of: DD mmm YYYY. This comment is posted on 23 NOV 2023, for example.
- I do prefer the abbreviated month with the yyyy mmm dd format. It makes things relatively easy to sort but you also don't have to worry about confusing others if you are referring to the 10th month or day for example.
The only correct format. Least to most specific.
Used to be my account name on a different website social media aggregator.
Best nomenclature for sorting.
For Excel 100%

YYYY-MM-DD (honestly without dashes) is the only helpful format.

If you name all your files with this as a suffix then your files automatically sort versions of themselves in order when sorting by name.

ISO 8601 baby
Though it ought to be a prefix, not a suffix
You mean as a prefix, right?
- Their assumption is that the filename is the same otherwise e.g. myNotes20231122.txt
Came here to say this, I use DD.MM.YY in day-to-day stuff, but for files it's either YYYY_MM_DD or YY_MM_DD, the automatic ordering is beautiful
Yeah this method is superior for digital filing. I can't imagine the sorting clusters I'd have to go through to find what I want any other way

Not to us burgerland citizens! 🇺🇲🇺🇲🦅🦅💥💥
- Massive trucks that increase fatalities. Bald eagles that are endangered because of Americans, and sound like red tailed Hawks for some reason. Fireworks that are more heavily regulated than guns.
  I love Americans but your country is run like a ball of yarn in a box of cats.

YYYY-MM-DD in Hungary too, that us shit is totally non logical, i cant get used to it

This is literally the most logical method to name a date in text.
- In what text?
  In French we say “14 juillet 1789”
  We don’t even say “nth day of”
Fuckin wait until you hear how many feet are in a mile. You all should've waterboarded us harder while we were a young country.
- FIvE tOMaToeS
It's very easy to sort by this format, makes perfect sense.
- Easier to sort by YYYY-MM-DD than MM-DD-YYYY tho
We do that in Sweden as well. Our social security numbers are that plus 4 unique numbers. The beers I send out to stores have yyyy-mm-dd printed at the bottom.
- So no more than 10 thousands of Swedes may get an SSN at the same day (or be born at the same day even 🤔)?

This meme implies there's an equal battle between MM/DD/YY and DD/MM/YY, which is nonsense. Much like imperial units, only 'murica uses MM/DD/YY.

Oi guvnah, ow many stone chu weigh?
- Only one, but it has my exact weight
- If you look at the calendar, you'll see that we are not in 1900 anymore.
  No one I know measures their own weight in imperial.
- Talking about fuel efficiency in miles per liter 🤣
- I have 2 stones if that's what you're asking.
But 'murica is big.
- Only slightly bigger than Australia and Western Australia is nearly twice the size of Texas..
Liberia and Myanmar also use imperial units, but they're both starting to move towards metric in recent years so soon the US truly will be alone in that

It actually makes sense when you put YYYY/MM/DD in filenames as they will be sorted pretty neat (ex: reports)

Yeah for a lot of files you probably would sort by year in the end

It is arguably the best way to name large sets of indexed files on a filesystem.

I think that the best argument is that it makes sense when combined with hours minutes and seconds.
yyyy/MM/dd hh:mm:ss
Goes from large to small units.
It sorts
Japan's way, you mean?
- Yes, YYYY/MM/DD
Files already have computer readable dates that can be used to sort and organize them
- In certain instances that may not always be available.
  One example I can think of is when browsing on a NAS.

When you're naming a file, you can't use anything else.

You're not wrong. through much trial and error in the 1990s I learned this was the most efficient & accurate & chronologically searchable way to date things.

YYYY-MM-DD for files, DD-MM-YYYY for normal use

Wtf why
- Agreed, YYYY-MM-DD should be normal use
- So its possible to properly sort by date?
- Because for 99.99% of all situations, you'd already know what year and month it is, so the most readily available piece of information should be the day.
YYYYMMDD for files
DDDD DD for normal use

YYYY-MM-DD for everything digital, DD-MM-YYYY for everything IRL.

Iso date format. Anything to do with photos is best to have in this format at the start of the filename.

Iso date format. Anything ~~to do with photos~~ is best to have in this format at the start of the filename.
Fixt.
It also means that by default it'll sort by newest

I propose the use of MYDYDM format. So, October 15, 2023 will be written as 121350. Just to make it as confusing as possible.

And then convert that to hexadecimal, making it 1DA06
Welp. I need a bath now.
Amazing
We're also unduly forgetting about truly little endian date format: DD/MM/YYYY, for instance 52/11/3202 for this Saturday
Also we could just sort the numbers and omit leading zeroes, that way we can save some space, the same date would be 1122235

TBH, Japanese format makes sense when you use it to name files/directories, as sorting by "name" is equivalenti to sorting by "last modified".

equivalenti
Love typos that force me to read comments with an Italian accent
- I'm actually italian, lol, but that was a genuine typo.
- Free upvotes for both of you
Until you need to work across centuries. Then it's eating paste level.

Japan I can get behind but MM/dd/yyyy is just evil, why would you sandwich days between months and years? You monster

I'm an ISO 8601 guy but the MM/DD does make sense in American. We'll say Oct 20th for a date and then straight translate that to numbers 10/20. It makes more sense than counting in French. Ex. 60, 70, 80, 90
- Counting in French is an incredibly low benchmark. Nice try!
The only reason I could see is if you were speaking it. September 18th 2012 for example might sound a bit better than 18 September 2012.

What about YY/DD/MM?

Oh fuck off. ;)
- I'll fuck of when it's 2024/22/11.
- If that one doesn't tickle you, we do have more options to explore like MM/YY/DD or DD/YY/MM
  Hell, we even have options like MDY/MDY

Japan wins this one.

2023年12月22日

令和5年12月22日
- 令和五年十二月二十二日

DD/MM for readability, YYYY/MM/DD for alphabetical sorting that's also chronological.

Ironically, MM/DD/YYYY works better for chronological sorting than DD/MM/YYYY, so long as you don't go between years.
Didn't think I'd be saying this but the Americans have an edge over us Brits.
- By this logic one might say that DD/MM/YYYY works for alphabetical chronological sort if you don't go between months...
- Have another go at this train of thought, mate... You're basically saying "MM/DD" is better at sorting chronologically than "DD/MM", since the year part is taken out of the equation, which is already the established consensus, and not ironical whatsoever. And the ISO standard is already to use YYYY-MM-DD, so that's the winner IMO, hands down. Japan is simply following that but using a slash as the delimiter.
- Excuse me, sir, but WAT?
- When you search or do any stable sort, I would think you want your primary attribute to be the one with most finite values? That way you are front loading the pruning of the search space.
  So it's actually on favor of Japanese style

May I chime in with a DD MMM YYYY as in 22 NOV 2023

I chime in with a "haven't you people ever heard of... DDMMMYYY?"
- 23Nov023?
The real superior option (except when naming files)

The right answer is: https://en.wikipedia.org/wiki/Unix_time

Japan isn't on its own wavelength, most of East Asian does this, probably because they all decided they wanted to be like China: which was a government which governed more. https://youtu.be/Mh5LY4Mz15o?t=1m7s

Here is an alternative Piped link(s):
https://piped.video/Mh5LY4Mz15o?t=1m7s
Piped is a privacy-respecting open-source alternative frontend to YouTube.
I'm open-source; check me out at GitHub.

Hey… it sorts properly alphabetically

Only within the same century, which is an issue for those of us born last millennium (or managing systems from that time), and could be a real problem in 50-ish years when we could get the first duplicates.
Better to stick with YYYY-MM-DD for alphabetical sorting
*ASCIIbetically. The alphabet doesn’t know digits.

Military be like 23/NOV/2023

Its the same for all East Asian countries as well, but I guess slapping JAPAN on it means fast upvotes, like that "Place, Japan" meme.

I can't speak for everyone but I see something Japanese then I upvote it, doesn't matter what it is.
Sushi, Bullet train, Bonsai, Anime, Bukkake, Haiku

SQL HAS ENTETED THE CHAT;

Why would you save dates as a date format when you can save them as an int or string and make calculations more complicated

Japan I can get behind but MM/dd/yyyy is just evil, why would you sandwich days between months and years? You monster

It makes sense to either go general to specific or specific to general. MM-DD-YYYY is neither.

TIL that I'm Japanese

YY/MM/DD SUPREMACY

How about 0xYYYMDD or 0xYYYYMDD if you need years after 4095 for some reason.

Today is 0x7e7b16

Congrats, you made it even less practical. Why not make it binary if that's the goal?
- Nah. With binary, you can lose one hex digit AND the max year would be 2047 (11 bits year, 4 bits month, 5 bits day). What's not to like about hex anyway?

China does this too. I love getting files in this format.

Reiwa era enters the chat

Most of Japanese hates the arbitary currender year resetting at each new emperor enthronrment. The conversion is ass and no one knows when it changes (bound to emperor's health) . Worst is its official year that govmt body accepts.

Real Estate Institute of Western Australia?
What do you mean you can't translate instantly between era year and Gregorian year?
- You are likely to only refer more than current era. If you're writing govmet grant application, renewing licence or certificate, chances are you mention events hapenned in previous era. You look up table for when the previous era started and ended, which era said year falls into, then convert for each year, each era. Extra minutes wasted every time instead of simply writing in Gregorian year.

There is of course a relevant xkcd page

Don't ask how they count the years tho

The truly enlightened interleave the numerals: YMD/YMD

The UK driving licence has birthdate as YMMDDY in the licence number. Totally uncrackable encryption.

Yeah but half the time is actually: EYY/MM/DD. Like this year is 令5/MM/DD.

And some years have two values, 2019 was both 平31, from 01/01 until 04/30, then 令1 from 05/01 onwards.

Is the kanji the name of the period the year belongs to or something? That looks interesting. Where can I find out more?
- Yup, it's a single character from the name of the era, and the era changes every time the emperor does.
- https://en.wikipedia.org/wiki/Japanese_era_name
Wat? Like their alphabet, do the Japanese have some double system?
China does this normally. Either YYYY.MM.DD OR YYYY年MM月DD日
- Yes, they have two date systems in common use. It's only the year that changes though. And there's no way to confuse the two, usually. If you write "2023" instead of "令5" it's pretty obvious. I suppose there is a potential for confusion if one just writes a two-digit year though.