All about dates and date related counters（日、週、月、年、才、歳）

Counter for days（日）

The ～日 counter is used to count days, or to state the day of the month. It can be pronounced using either the Japanese pronunciation of「～か」or the Chinese pronunciation of「～にち」. The Kanji for 日 「ひ」is also used for the sun, a day being one cycle of the earth and the sun returning back to the same position in the sky.

This is one of the more difficult counters to learn as there is quite a number of rules built around it.

Note on pronunciation

• When stating the first day of a month, 一日 is pronounced as 「ついたち」, when talking about a period of 1 day, 一日 is pronounced as 「いちにち」.「ついたち」is a special pronounciation that uses neither the 「～か」or 「～にち」pronunciations of 日. The word comes from the period of time when Japan used the lunar calendar to measure months, and the pronunciation is derived from the shape of the moon on the first day of the month using the Kanji for the moon 月 「つき」and to stand 立「たち」.

For 2 - 10 days the Japanese pronunciations of numbers is used.

• 二日 is pronounced「ふつ・か」
• 三日 is pronounced「みっ・か」
• 四日 is pronounced「よっ・か」
• 五日 is pronounced「いつ・か」
• 六日 is pronounced「むい・か」
• 七日 is pronounced「なの・か」
• 八日 is pronounced「よう・か」. Be careful as this sounds very similar to 四日「よっ・か」.
• 九日 is pronounced「ここの・か」
• 十日 is pronounced「とお・か」

After 10, the Chinese pronounciations are used, with the following exceptions

• Any number ending in ～四日, can be pronounced using either 「～よっ・か」or「～よん・にち」, with「～よっ・か」being more common when talking about the day of the month, and 「～よん・にち」being more common when talking about a period of time. For example, 十四日 is commonly pronounced 「じゅう・よっ・か」for the 14th of the month, and 「じゅう・よん・にち」for a period of 14 days.
• ～九日 is pronounced「～く・にち」
• 二十日 is pronounced using the Japanese pronunciaton「はつか」

Counter for weeks（週）

The ～週「～しゅう」counter is used to count weeks. When talking about a period of weeks, it usually has the suffix ～間「～かん」appended to it.

Note on pronunciation

• 一週 is pronounced「いっ・しゅう」
• 八週 is pronounced「はっ・しゅう」or「はち・しゅう」
• 十週 is pronounced「じっ・しゅう」or「じゅっ・しゅう」

Months of the year（月）

The ～月「～がつ」counter is used for the month of the year, the first month being January, the second month being February etc. You may notice that the Kanji for months uses the same Kanji used for the moon 月「つき」, this is because of in older times the full cycle of a moon was used to measure a month passing (28 to 29 days).

Note on pronunciation

The Chinese pronunciations are used for all the months of the year, including the numbers (4, 7 and 9) which normally use the Japanese pronunciations.

• 四月 is pronounced「し・がつ」
• 七月 is pronounced「しち・がつ」
• 九月 is pronounced「く・がつ」

You may occasionally see 一月「ひと・つき」or 二月「ふた・つき」used to describe a period of 1 month, or 2 months respectively, though this usage is less common.

Counter for months（ヶ月）

When talking about a number of months, rather than the month of the year, the counter ヶ月「か・げつ」is used.

This counter may be written a number of alternative ways, using the Hiragana for ka （か月）, the Katakana for ka（カ月）, a smaller version of the Katakana for ka（ヵ月）, the 個 counter （個月）or its older form （箇月）, or the Katakana for ke（ケ月）.  In all these cases it is pronounced 「か・げつ」.

Like the other counters for time, it usually has the suffix ～間「～かん」appended to it when talking about a period of months.

Note on pronunciation

• 一ヶ月 is pronounced「いっ・か・げつ」
• 六ヶ月 is pronounced「ろっ・か・げつ」
• 八ヶ月 is pronounced「はち・か・げつ」or「はっ・か・げつ」
• 十ヶ月 is pronounced「じゅっ・か・げつ」or「じっ・か・げつ」
• 百ヶ月 is pronounced「ひゃっ・か・げつ」

Counter for years（年）

The ～年「～ねん」counter is used to count years or to state the current year. When talking about a period of years, it usually has the suffix ～間「～かん」appended to it.

Note on pronunciation

• 四年 is pronounced「よ・ねん」
• 九年 is pronounced「きゅう・ねん」or「く・ねん」

Writing Dates in Japanese

Dates in Japanese are written in the order of Year Month Day. The day of the week (usually just abbreviated to the first Kanji) can also be added in brackets afterwards.

In horizontal script, dates are most commonly written using arabic numbers with their counters. Two digit years abbreviations in the form of YY/MM/DD or YY.MM.DD are also common. For example the 21st of January 2022 could be written as:

• 2022年01月21日（金）
• 22/01/21
• 22.01.21

In vertical script you are more likely to see Kanji used for numbers. Though this could be either in the normal method of writing numbers using Kanji, or a mix of using the arabic system with the Kanji numeral replacing the arabic digit and using 〇「まる」 for 0.

• 二千二十二年一月二十一日
• 二〇二二年一月二一日

Further reading: https://japanese.stackexchange.com/questions/17423/are-kanji-typically-used-in-times-and-dates/17450#17450

Japanese Imperial Calendar

While Japanese commonly use the Gregorian calendar system for writing years, in official documents the year is based on which year it is within the reign period of the Japanese Imperial Emperor. A new era name is assigned the day a new Emperor ascends to the throne and ends on the day of the Emperor's death.

The era names that are used in modern Japanese are listed below:

• 1868-1912 : 明治「めい・じ」
• 1912-1926 : 大正「たい・しょう」
• 1926-1989 : 昭和「しょう・わ」
• 1989-2019 : 平成「へい・せい」
• 2019- : 令和「れい・わ」

To write a year using the Japanese Imperial Calendar, the era name precedes the year with the era. So the 21st of January 2022 would be written as

• 令和4年1月21日（金）

Further reading : https://notesofnomads.com/japanese-date-system/

Counter for age in years（歳／才）

The 歳「さい」counter is used for counting the age of humans and animals. It can also be written using the simpler Kanji 才「さい」. For children aged up to 10 the generic つ counter is also commonly used for age.

Note on pronunciation

• 一歳 is pronounced「いっ・さい」
• 八歳 is pronounced「はっ・さい」
• 十歳 is pronounced「じっ・さい」or「じゅっ・さい」
• 二十歳 is pronounced「はたち」