The 24 solar terms
— jeol and gi, and the twelve that Saju uses
Of the 24 solar terms, the only ones that
change the Saju month are the 12 jeol (節).
The other 12 are gi (氣) — they simply mark the middle of the month
Those small words printed in the corner of the calendar — Gyeongchip (Awakening of Insects), Cheongmyeong (Clear and Bright), Cheoseo (End of Heat) — are the 24 solar terms. They're neither holidays nor days off, yet in Saju they matter more than the 1st of the month on your calendar. That's because in Saju, your birth month is set by the solar terms, not by the calendar.
In this article 8 topics
Are solar terms lunar or Gregorian?
Neither. Solar terms are set by the sun's position. The Earth's orbit around the sun is divided into 24 parts, and the moment each point is passed is given a name.
That's why their Gregorian dates stay almost fixed every year. Ipchun is always February 3–5, and Haji is always around June 21. Because they're printed on lunar calendars, people take them for lunar dates, but lunar dates jump around by as much as a month from year to year. Solar terms don't.
A solar term is not a date but a moment. The accurate way to put it isn't “Ipchun is February 4” but “Ipchun is February 4 at 10:46.”
How do jeol (節) and gi (氣) differ?
Not all 24 carry the same weight. At 15-day intervals, jeol and gi take turns.
| Category | Count | Role | Name |
|---|---|---|---|
| Jeol (節) | 12 | The boundary where the Saju month changes | Ipchun · Gyeongchip · Cheongmyeong · Ipha · Mangjong · Soseo · Ipchu · Baengno · Hallo · Ipdong · Daeseol · Sohan |
| Gi (氣) | 12 | Marks the middle of the month (doesn't change the month) | Usu · Chunbun · Gogu · Soman · Haji · Daeseo · Cheoseo · Chubun · Sanggang · Soseol · Dongji · Daehan |
When a jeol passes, the two characters of your Saju month pillar (月柱) change. After Ipchun it's the Tiger month, after Gyeongchip the Rabbit month, and so on. A gi only deepens the character of its month; it doesn't turn to the next one.
| Jeol (節) | Approx. date | From here | Earthly Branch |
|---|---|---|---|
| Ipchun | Around Feb 4 | Tiger month · the Saju new year begins | In (寅) |
| Gyeongchip (驚蟄, Awakening of Insects) | Mar 5–6 | Rabbit month | Myo (卯) |
| Cheongmyeong (清明, Clear and Bright) | Apr 4–5 | Dragon month | Jin (辰) |
| Ipha (立夏, Start of Summer) | May 5–6 | Snake month | Sa (巳) |
| Mangjong (芒種, Grain in Ear) | Jun 5–6 | Horse month | O (午) |
| Soseo (小暑, Minor Heat) | Jul 6–7 | Sheep month | Mi (未) |
| Ipchu (立秋, Start of Autumn) | Aug 7–8 | Monkey month | Sin (申) |
| Baengno (白露, White Dew) | Sep 7–8 | Rooster month | Yu (酉) |
| Hallo (寒露, Cold Dew) | Around Oct 8 | Dog month | Sul (戌) |
| Ipdong (立冬, Start of Winter) | Nov 7–8 | Pig month | Hae (亥) |
| Daeseol (大雪, Major Snow) | Dec 6–7 | Rat month | Ja (子) |
| Sohan (小寒, Minor Cold) | Jan 5–6 | Ox month | Chuk (丑) |
Why does the exact time matter?
Because some people really are born right on the boundary. In 2027, Ipchun is February 4 at 10:46 a.m. Someone born at 9 a.m. that day and someone born at 12 noon have completely different year and month pillars — all four characters.
If you know only the date and not the time, you'll get it wrong at this boundary. That's why Mutal Unnie calculates solar-term entry times to the minute. I go into this further in Why Ipchun is the Saju new year.
Why do solar-term times differ between sources?
Because they're based on different standard times. The moment a solar term occurs is the same all over the world. What differs is which country's clock it's written down in.
Korea Standard Time is based on 135°E and China Standard Time on 120°E, so they're exactly 1 hour apart. A manseryeok that copies Chinese data as-is shows entry times an hour early. If only the time is off, that's not so bad, but when the entry falls in the 0:00 hour after midnight Korean time (the 11 p.m. hour in China), even the date splits by a day.
A real example — In 2027, Sanggang (霜降, Frost's Descent) falls on October 24 at 00:32 Korean time, but on October 23 at 23:32 Chinese time. Same moment, different date. The same goes for Ipdong (立冬, Start of Winter) in 2027 (Korea: November 8 at 00:38 / China: November 7 at 23:38).
I've gathered this and the other points where manseryeok results diverge in Why manseryeok apps give different results.
Entry times by year
2027: the 24 solar terms
Ipchun on February 4 at 10:46, Dongji on December 22 at 11:42. Sanggang and Ipdong fall on different dates in Chinese time.
By year2028: the 24 solar terms
Ipchun on February 4 at 16:31, Dongji on December 21 at 17:19. It's a leap year, so Haji falls in the early hours of June 21.
The solar terms one by one
Ipchun — the Saju new year
The real boundary — not January 1, and not Seollal either. If you were born before Ipchun, you use the previous year's stem-branch pair.
Gi · Rat monthDongji — the longest night
The day for patjuk, and once the day people counted the year from.
Jeol · Dragon monthCheongmyeong — the original Son-eomneun-nal
The solar term that goes hand in hand with Hansik. There's a reason people moved house and tended graves then.
Gi · Horse monthHaji — the longest day
The day yang energy peaks — and, for exactly that reason, the day it starts to turn.
Which solar-term period does my Saju fall in?
Enter your birth date and time to see right away which solar-term period you fall in, and whether you're right on a boundary.
→ Open the Manseryeok calculator
When the solar term changes, your rhythm changes too
Comparing your Eight Characters with today's solar term is free on Mutal Unnie.
Get the app for iPhone & AndroidFAQ
Are the 24 solar terms lunar or Gregorian?
Neither. They're a solar-calendar concept set by the sun's position, so their Gregorian dates stay almost fixed from year to year. They're only mistaken for lunar because they're printed on lunar calendars.
How do jeol (節) and gi (氣) differ?
Only the 12 jeol change the Saju month. The 12 gi simply mark the middle of the month. The jeol are Ipchun, Gyeongchip, Cheongmyeong, Ipha, Mangjong, Soseo, Ipchu, Baengno, Hallo, Ipdong, Daeseol and Sohan.
Why do solar-term times differ from one manseryeok to another?
Because they use different standard times. Korea (135°E) and China (120°E) are 1 hour apart, so a manseryeok that uses Chinese data as-is shows entry times an hour early. Near midnight, even the date can differ.
What does knowing the solar terms tell you in Saju?
They set the two characters of your month pillar, the pillar for the month you were born in. The month pillar carries the energy of the season. The age at which your Daeun (10-year luck cycle) begins is also calculated from the distance between your birth date and the nearest solar term.