The solar-term calendar — Saju’s real calendar
Why the Saju new year falls on 4 February
A story to start
Koreans used to paste a spring blessing on the gate at Ipchun. Why wish for the new year on 1 January but hang the blessing in early February? Because in Myeongri, Ipchun is the real New Year’s Day. The calendar used to pull a chart is neither the solar nor the lunar calendar but a third one — the calendar of solar terms. Not knowing this makes the whole chart of anyone born in January wrong. Let’s settle it today.
🏺 A spoonful of origin
The twenty-four solar terms divide the sun’s path along the ecliptic into twenty-four. Ipchun, Usu, Gyeongchip, Chunbun… it was the survival calendar of an agricultural society. People often assume it is lunar, and because the terms are fixed by the sun’s position they in fact pair almost exactly with the solar calendar (Ipchun falls on 3–5 February every year). That Saju takes the terms as its reference means Saju is a study of solar energy — which is to say, of season.
📖 The main point — where the year and the month change
Two lines of rule. ① The year pillar changes at Ipchun: someone born on 3 February 2026 is still in the Eulsa year (snake); from 4 February it is Byeong-o (horse). ② The month pillar changes at each month’s major term: Ipchun to Gyeongchip is the first month (In month), Gyeongchip to Cheongmyeong the second (Myo month)… twelve terms make twelve month boundaries. So the Saju “month” turns over around the 4th to 8th of each calendar month. That is why the monthly fortune on this site notes that the month boundary follows the solar terms.
🔍 In practice
Pull charts for people you know born in January or early February. Seeing for yourself a case where the calendar year and the Saju year (the animal) differ is the best study there is. “Wait — I’m an ox, not a tiger?” The shock of that moment makes you never forget the term calendar. This site applies the Ipchun boundary automatically, so just look at the year pillar on the result screen.
🗣️ The story people tell
The dog days of summer aren’t among the twenty-four terms. They are “miscellaneous terms,” fixed by counting Gyeong days — days whose Stem is Gyeong Metal — from the solstice and from Ipchu. A day of Metal was chosen to restore a body worn down by heat (Metal melting under Fire) — so there is a Stem calendar inside even a bowl of summer chicken soup.
🧭 Working through the situations
The term calendar causes practical trouble at two moments. First, correcting the animal for anyone born in January or early February — someone born on 20 January 1995 is a pig by the calendar and, being before Ipchun, belongs to the 1994 Gapsul year (dog) in Saju. That can be a shock to someone who has lived as a pig their whole life, so break it gently. Second, birth on a term day — born on Gyeongchip, you have to check the exact <i>time</i> Gyeongchip began before the month pillar is settled. Term times vary year to year (morning or night) and can be checked in a calendar app or from an astronomical institute. Checking that boundary is the detail that separates professional from amateur.
❓ Frequently asked
Q. So the lunar birthday has nothing to do with a chart? Astonishingly, yes. Saju uses the solar-term calendar, which is solar, not the lunar one. “You need a lunar birth date to read a chart” is a common misconception — what you need is the solar date and time. Traditional seasonal customs such as Tojeong Bigyeol did use the lunar calendar. Q. How many of the twenty-four terms does Saju use? Only the twelve major terms that mark month boundaries (Ipchun, Gyeongchip, Cheongmyeong, Ipha, Mangjong, Soseo, Ipchu, Baengno, Hallo, Ipdong, Daeseol, Sohan). The other twelve are signposts in the middle of a month. Q. Why do the term dates shift slightly each year? Because Earth’s orbit isn’t exactly 365 days. That is why Ipchun moves between 3 and 5 February.
✏️ Today’s one step
Find this year’s Ipchun date, write it down and note “this is my chart’s New Year’s Day.” Then check whether your birthday falls before or after that month’s term. If you can feel the thrill of a month pillar changing on one day’s difference, you already have the intermediate constitution.