The Ten Heavenly Stems: Names, Elements and Images

The ten heavenly stems are the upper half of every pillar. Each one is a single element in either its yang or its yin form, and the tradition gives each a picture from nature to make its character easy to remember.

What the stems are

The heavenly stems (天干, Korean 천간) are ten signs used in a fixed order: 甲 乙 丙 丁 戊 己 庚 辛 壬 癸. In old China they served as a count of ten, for example for the days of a ten-day week, long before they were combined with the twelve branches into the sixty-step cycle.

In a Four Pillars chart every pillar has a stem on top and a branch below. The stems are called heavenly because they are read as the visible, outward side of each pillar, while the branches are the earthly ground underneath. Of the four stems in a chart, the one on top of the day pillar is special: the tradition calls it the day master and reads the whole chart from its point of view.

The ten stems at a glance

The order simply walks through the five elements, giving each a yang form first and a yin form second. The image column translates the short Korean descriptions used inside the haru app.

Reading the pairs

The images are easiest to understand in pairs. Each element appears twice, and the yang stem is the large, open, outward version while the yin stem is the smaller, closer, more inward one. 甲 is the tall tree and 乙 the vine that finds its way around obstacles. 丙 is the sun that lights everything at once and 丁 the candle that lights the space right beside it. 戊 is the mountain that stands firm and 己 the field that is tended and grows things. 庚 is raw rock and iron, 辛 the cut and polished gem. 壬 is the broad river and sea, 癸 the rain and dew that seep quietly in.

The haru app pairs each image with a short description of temperament. For example, the tradition reads 甲 as an upright nature that wants to grow straight up, 丁 as a warm nature that lights up the people nearby, and 癸 as a quiet nature that soaks in and observes. These are traditional pictures for thinking about a chart, not descriptions that fix who anyone is.

Finding the stem of a year

Because the stems repeat every ten years, the last digit of a year tells you its stem. The rule is to subtract 4 and take the remainder after dividing by 10. For 2026: 2026 minus 4 is 2022, and 2022 mod 10 is 2, the third stem counting from 0, which is 丙. The facts file confirms it: the 2026 year pillar is 丙午. In the same way 2024 is 甲辰 and 2033 is 癸丑.

One caution: the calendar year for pillars does not start on 1 January but at the solar term Start of Spring (立春) in early February, so a birthday in January belongs to the previous year's stem. The year-pillar page explains this in detail.

Where the stems go next

Stems do not only sit on top of pillars. Each branch also carries one, two or three stems inside it, called hidden stems, and the stems of a chart relate to the day master through the ten gods. Both ideas build directly on the ten signs in the table above.

Questions

Why are there ten stems and not five?

Each of the five elements appears once in yang form and once in yin form, so 5 times 2 gives 10.

Is 甲 the best stem because it comes first?

No. The order is only a sequence through the elements. The tradition gives no stem a higher rank than another.

How do I find the stem of my birth year?

Subtract 4 from the year and take the last digit of the result: 0 is 甲, 1 is 乙, and so on up to 9 for 癸. If you were born before Start of Spring in early February, use the previous year.

What is the day master?

It is the stem on top of the day pillar. The tradition reads every other character in the chart in relation to it.

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Traditional Four Pillars (myeongni) and yin-yang five-element interpretation. Not a medical diagnosis or advice.