Japan's 72 Microseasons: Which One Were You Born In?

Updated October 15, 2026

Japan's traditional calendar divides the year into 72 microseasons, or kō, each about five days long and each named after a small change in nature: "East wind melts the ice," "First cherry blossoms," "Crickets chirp by the door." Every birthday falls in one of them.

To find yours, look up your birth month and day in the full list of 72 at the end of this article: your microseason is the last one that starts on or before your birthday. Near a boundary the answer can change with the year. A March 25 birthday, for example, falls in "Sparrows start to nest" in some years and in "First cherry blossoms" in others.

The sections below explain how the microseasons are counted, why the list used in Japan differs from the older Chinese one, and why the boundaries shift by a day. To look up an exact date, enter it in the free night sky on the day you were born preview, which shows the microseason for the date you enter.

24 solar terms, each split in three

The microseasons are a finer division of the 24 solar terms (sekki). A solar term begins each time the Sun moves another 15° along the ecliptic, its yearly path through the sky; Risshun, the start of spring, is at 315° (National Astronomical Observatory of Japan, 24 solar terms, in Japanese). Each solar term is split into three microseasons, the first, middle and last, so 24 × 3 = 72 (National Astronomical Observatory of Japan, Koyomi Wiki: 72 microseasons, in Japanese).

Today the usual way to date them, and the one our calendar engine uses, is by the Sun's position: a new microseason begins each time the Sun has moved another 5° along the ecliptic, and the day that contains that moment in Japan time is its first day. The cycle starts at Risshun with no. 1, "East wind melts the ice," at 315°.

Because the Earth moves faster in its orbit in early January than in early July, the Sun's 5° steps take different amounts of time. From 1950 to 2030, a microseason lasted between 4.90 and 5.25 days, so on the calendar most last five days and some four or six.

Japan's own names

The 72 microseasons came from China, where they first entered the calendar with the Zhengguang calendar of the Northern Wei dynasty. Until the 1680s, Japan used a list taken from Tang-dynasty Chinese calendars. Its names include "otters lay out fish" (獺祭魚) and "hawks turn into doves" (鷹化為鳩).

Shibukawa Harumi, who made the first calendar devised by a Japanese astronomer, the Jōkyō calendar of 1685 (National Diet Library, The Japanese Calendar), rewrote the list to fit Japan's climate, plants and animals. It was revised again in part for the Hōreki calendar of 1755, and those are the names used in Japan today (NAOJ, Koyomi Wiki, linked above). In the 4th place, where the Tang list has the otters, Japan has "Rain moistens the soil" (土脉潤起); in the 9th, instead of the hawks, "Caterpillars become butterflies" (菜虫化蝶).

Comparing the two lists in the National Astronomical Observatory of Japan's table, 52 of the 72 places have a different name, and 44 of the Japanese names do not appear anywhere in the Tang list. The names in this article and on our print are the Japanese ones.

How the dates were set has changed too. Older Japanese almanacs split the year into 72 equal stretches of time. The Tenpō calendar of 1844 stopped assigning microseasons to dates, and the government's abridged almanacs of 1874 to 1884 printed the three names together under each solar term (NAOJ, Koyomi Wiki). Dates found in older sources can therefore differ from ours near a boundary.

Which microseason were you born in?

1. Find your birth month and day in the column "Start date, 1950–2030" of the table below. Your microseason is the last one that starts on or before your birthday.
2. If your birthday is on one of the dates in that range, it is near a boundary, and the answer depends on the year. Enter your full date in the night sky preview to see which one applies.
3. Microseasons are counted in whole days in Japan time. If you were born outside Japan, the preview looks up the date you enter in Japan's calendar; the time and the city do not change the microseason.

The same birthday in different years

Take March 25. "First cherry blossoms" (桜始開), the 11th microseason, starts when the Sun reaches 5°, on March 25 or 26. A March 25 birthday therefore falls either at the end of "Sparrows start to nest" (雀始巣, no. 10) or on the first day of "First cherry blossoms."

From 1950 to 2030, March 25 was in "First cherry blossoms" in 26 years and in "Sparrows start to nest" in 55 years. The years with cherry blossoms were 1968, 1972, 1976, 1980, 1984, 1988, 1992, 1996, 1997, 2000, 2001, 2004, 2005, 2008, 2009, 2012, 2013, 2016, 2017, 2020, 2021, 2024, 2025, 2028, 2029 and 2030. In 2026, March 25 is in "Sparrows start to nest."

The pattern follows leap years. A calendar year of 365 days is about a quarter of a day shorter than the Sun's year, so each year the Sun reaches 5° about six hours later by the clock, until a leap day sets it back by a day. Boundaries therefore fall earliest in leap years and the years right after them. Over the decades the boundary has also drifted slowly earlier, which is why the cherry blossoms come more often from the 1990s on. The same thing happens around every microseason: the column "Start date, 1950–2030" shows the spread for each one.

Your microseason on the night sky print

The night sky on the day you were born print is a star map for your date, time and city. Next to the map it shows the microseason of that date: the name in kanji, the English translation, the Japanese reading in Latin letters, its number out of 72 and its solar term. A March 25, 2026 birthday, for example, shows 雀始巣, "Sparrows start to nest," Suzume hajimete sukū, No. 10 of 72, in the solar term Shunbun (春分). The article Are custom star maps accurate? explains what the star map needs in order to show the real sky of that night, and how to check it yourself. For a map of the night you met or your wedding date, see what to put on an anniversary star map.

The print shows only the microseason's name; its start and end dates are in the table below. The English translations are short and free, written with AI assistance; they are the same on the print and in the table below. The print also shows the Japanese zodiac year, which changes at Risshun like the microseasons (how to find your Japanese zodiac year), and the Moon's phase (what the Moon looked like on the day you were born).

All 72 microseasons

The dates in "Starts in 2026–27" are the first days, in Japan time, of the microseasons from Risshun 2026 to Risshun 2027. Each microseason lasts until the day before the next one starts. In other years a start date can be a day earlier or later; "Start date, 1950–2030" gives the range. "Sun" is where the Sun was on the ecliptic at the start, in degrees counted from its position at the March equinox.

About this article

The start of each microseason is the day, in Japan time, that contains the moment the Sun reaches a multiple of 5° on the ecliptic (its apparent ecliptic longitude, in astronomers' terms). The moments are calculated with Swiss Ephemeris, a widely used library for computing the positions of the Sun, Moon and planets. Every start from 1950 to 2031 in our calendar engine was checked against a separate calculation, and those that begin a solar term fall on the same day as in the National Astronomical Observatory of Japan's published almanac tables, within a minute of the published time, for 1950 to 1999. The kanji and Japanese readings match the National Astronomical Observatory of Japan's list.

The English text of this article was written with AI assistance. The dates and solar longitudes in the examples and the table are calculated by our software, not generated by AI.