Rejoice, my fellow human! For it's one of the those unicorn-level-rare times that the Japanese language way actually makes more sense than the western languages way!
The Japanese date format is year, month, day, or 2017年3月12日 (ni sen jyuu nana nen, san gatsu, jyuu ni nichi), literally "year 2017, month 3, day 12."
For partial dates, dates without years, it's just month and day: san gatsu jyuu ni nichi 3月12日, "month 3, day 12." Since months, days and years in Japanese are just counters, all you need to know are the numbers in Japanese and you'll be able to read and write any date.
Years may also be written with Japanese imperial calendar years instead of Gregorian years. heisei jyuu nana nen, san gatsu, jyuu ni nichi 平成29年3月12日.
Because of this order, the "date" in Japanese may be called nengappi 年月日, literally "year, month, day." A given "date," the date of something, is also often called hidsuke 日付. Another common word is seinengappi 生年月日, which means "birth date." Note this isn't used the same way as tanjoubi 誕生日, which is a person's "birthday."
Why Japanese Dates Make More Sense
Now, I'm pretty sure you got curious when I said the Japanese date format make more sense than our western date formats. After all, Japan? Making sense? In their chaotic Japanese language where nothing ever makes sense nonetheless?! What is this madness?!
But I'm not joking. The International Organization for Standardization, the people who create standards the whole world uses so stuff like the internet works alright, had drafted decades ago the famous ISO 8601 standard, which aimed to standardize date formats.
In this international standard, dates are written like this: 2017-03-12, YYYY-MM-DD, four digit year, two digit month, two digit day, which is just like Japanese (except it isn't required to use 2 digit months and days).
Why The Year First?
The year first makes more sense because the biggest, that is, the most significant component should come first. Think of the number 123. The digit 1 is smaller than 2, but because 1 comes before 2 in 123 the 1 (hundred) is the bigger number.
- 2017-03-12 (biggest, big, small)
- 18:35 (hour is big, minute is small)
- 5' 10" (feet big, inches small)