Your Day Master is a single character: the heavenly stem of your day pillar. A BaZi chart has four pillars, for the year, month, day and hour of birth, and each pillar has a stem on top and a branch below. The stem of the day pillar is the one the rest of the chart is read against.
The Day Master is one of ten stems
There are ten stems. Each is one of the five elements, Wood, Fire, Earth, Metal or Water, in a yang or a yin form. The calculator writes the name with its pinyin, its element and its characters, for example Jia Wood (甲木).
| Stem | Name on the result screen | Polarity | Birth stage sits on | Peak stage sits on |
|---|---|---|---|---|
| 甲 | Jia Wood (甲木) | yang | 亥 Hai | 卯 Mao |
| 乙 | Yi Wood (乙木) | yin | 午 Wu | 寅 Yin |
| 丙 | Bing Fire (丙火) | yang | 寅 Yin | 午 Wu |
| 丁 | Ding Fire (丁火) | yin | 酉 You | 巳 Si |
| 戊 | Wu Earth (戊土) | yang | 寅 Yin | 午 Wu |
| 己 | Ji Earth (己土) | yin | 酉 You | 巳 Si |
| 庚 | Geng Metal (庚金) | yang | 巳 Si | 酉 You |
| 辛 | Xin Metal (辛金) | yin | 子 Zi | 申 Shen |
| 壬 | Ren Water (壬水) | yang | 申 Shen | 子 Zi |
| 癸 | Gui Water (癸水) | yin | 卯 Mao | 亥 Hai |
The last two columns come from the twelve life stages, a cycle that places each stem somewhere on the twelve branches. "Birth" and "Peak" are two of its twelve names. Yang stems run the cycle forward through the branches and yin stems run it backward, which is why the two columns move in opposite directions.
The ten stems repeat every ten days
The day stem moves one step each day and comes back to the same stem every ten days. The days around Lichun in 2027 show the run in order, counted at noon in New York:
| Date (noon, New York) | Day pillar | Day Master |
|---|---|---|
| February 1, 2027 | 辛亥 | Xin Metal (辛金) |
| February 2, 2027 | 壬子 | Ren Water (壬水) |
| February 3, 2027 | 癸丑 | Gui Water (癸水) |
| February 4, 2027 | 甲寅 | Jia Wood (甲木) |
| February 5, 2027 | 乙卯 | Yi Wood (乙木) |
| February 6, 2027 | 丙辰 | Bing Fire (丙火) |
So two people born a day apart have different Day Masters, and two people born ten days apart share one. The branch under the stem runs on a twelve-day step at the same time, which is why the full day pillar repeats only every sixty days.
The day turns at solar midnight here
This calculator turns the day at solar midnight, the moment the Sun is lowest below your birthplace, not at 00:00 on the clock. Solar midnight sits a few minutes to more than an hour away from clock midnight, depending on where you are in your time zone, the time of year, and whether clocks are on daylight time.
| Place | Solar midnight, January 15, 2027 | Solar midnight, July 15, 2027 |
|---|---|---|
| New York | 12:06 am EST | 1:03 am EDT |
| Detroit | 12:42 am EST | 1:39 am EDT |
| London | 12:10 am GMT | 1:07 am BST |
| Dublin | 12:35 am GMT | 1:32 am IST |
In summer the gap passes an hour, because daylight time moves the clock forward while the Sun stays where it was. A birth at 1:15 am on July 15, 2027 in Detroit still has the day pillar of July 14.
The size of the correction depends on the city. On February 3, 2027, true solar time ran behind the clock by these amounts:
| City | Solar time minus clock time |
|---|---|
| New York | −9.8 min |
| Toronto | −31.3 min |
| Detroit | −46.0 min |
| Chicago | −4.3 min |
| El Paso | −19.7 min |
| Los Angeles | −6.8 min |
| Vancouver | −26.3 min |
| Halifax | −28.1 min |
| London | −14.3 min |
| Glasgow | −30.8 min |
| Dublin | −38.8 min |
The same correction can move the hour pillar too. That is a separate step, and the calculator applies both.
Born between 11 pm and midnight
The hour pillar works in two-hour blocks, and the first block of the BaZi day, the Rat hour (子), starts at 11 pm solar time, an hour before solar midnight. That leaves one hour where the hour block and the day do not line up, and BaZi traditions handle it in more than one way.
This calculator keeps the day pillar of the evening until solar midnight. For a birth in that last hour it gives the Rat hour, and counts the hour stem from the next day's stem, the day that the Rat hour opens.
So a birth at 11:30 pm solar time and a birth at 12:30 am solar time share the Rat hour branch, but not the Day Master.
How the Day Master names everything else
Once the Day Master is fixed, every other stem in the chart gets a name for its relationship to it. There are ten names, from Companion to Direct Resource, and each comes from two facts: whether the other stem's element is the same, produced, controlled, controlling or producing, and whether its polarity matches.
That is why the same year can sit differently in two charts. The table on the 2027 page shows what the year's two characters are called for each of the ten Day Masters.
How 丁未 meets each Day Master →
What the calculator shows next to it
The result screen states the Day Master with its polarity, then how well it is supported by the rest of the chart. The line reads in this form: "Day Master Jia Wood (甲木), yang. Support reads Balanced."
- Support score, from 0 to 100. In the calculator's own words: "Neither end is better."
- Strength label, one of three: Strong, Balanced or Weak.
- Five roles the other elements play around the Day Master: Peers, Support, Output, Wealth and Authority.
These are labels for structure. The score measures how much of the chart supports the Day Master's element. It does not grade the person.
If you do not know your birth time
Without a birth time, the calculator leaves out the hour pillar and keeps the other three. In its words: "Everything else is unchanged." The day pillar then follows the calendar date of birth.
That is safe for most of the day. It is not safe for a birth shortly after clock midnight, because solar midnight can come later. Before a full reading is written, the confirmation screen names your birthplace's solar midnight and asks you to check.
Why the BaZi year turns at Lichun →
Find yours
The free BaZi calculator takes your date, time and place, applies the solar-time correction for your birthplace, and shows your Day Master with the three readings above.