Why You Got These Eight Characters — Reading Your Own Calendar

You've probably seen unfamiliar characters like 甲子 (Gap-ja) or 丁丑 (Jeong-chuk) show up in a calendar or a daily reading, and wondered why those particular characters — and how the two get paired up. This chapter unpacks that.

The Ten Thousand Year Calendar (萬歲曆) is an almanac table that records the dates of a long span in stems and branches (干支). To read a BaZi chart you need the stems and branches of the year, month, day and hour of a birth, and this table is where you look them up. It used to mean opening a thick book and tracing by hand; today the same rules are done by calculation.

Pairing the ten heavenly stems (天干) with the twelve earthly branches (地支) gives sixty combinations. These sixty attach in turn to the year, month, day and hour, and with one character above and one below in each of the four pillars you get eight characters in all. This is what people mean by BaZi — the Four Pillars and Eight Characters (四柱八字).

So out of those sixty combinations, why did you end up with exactly these eight characters? The answer is simple — they're just a record of where the sky and earth stood at the moment you were born. The one catch is that the cutoff points for that moment aren't quite the same as the calendar you're used to.

The Year Pillar and Month Pillar aren't set by the calendar — they're set by the solar terms (節氣). The year doesn't turn over on January 1st or Lunar New Year; it turns over at Ipchun, the Start of Spring (立春). The month works the same way — it starts not on the 1st but on whichever solar term opens that month. So someone born in early February, before Ipchun, still gets the previous year's stem-branch pair. Solar terms are an astronomical event tied to the sun's position, so they're calculated down to the exact minute.

The Day Pillar doesn't change at a solar term — it changes at midnight. More precisely, the day flips over the moment Zi hour (子時) begins, a boundary called Night Zi (夜子時). So if you were born after 11:30 p.m., the clock still says that day, but the Day Pillar is already calculated as the next day's.

Why 11:30 rather than exactly midnight? Because the meridian used to set standard time (135° East) sits about 30 minutes off from where the sun actually is over the Korean peninsula. So BaZi uses true solar time instead — time corrected to the sun's real position — and that shifts every hour-boundary 30 minutes earlier than the clock.

Now, how do you read two characters together? A pairing like 丁丑 is simply read straight through — the 丁 (Jeong) on top, then the 丑 (chuk) below, giving "Jeong-chuk." Stems and branches don't mix freely, though. A yang (陽) stem only ever pairs with a yang branch, and a yin (陰) stem only with a yin branch — which is why there are sixty possible combinations instead of a hundred twenty.

The elements above and below aren't always the same. In Jeong-chuk (丁丑), the top is Fire (火) and the bottom is Earth (土) — two different elements meeting in one pairing. So to really read a stem-branch pair, you need to look at the top and bottom characters separately. What each character carries was covered back in the "Nature of Stems and Branches" chapter.

Now, when you look at the two characters in a daily reading's calendar, you'll be able to see exactly what principle produced that pairing — and how to read it.