By now you have the conceptual foundation: fourteen stars from two Dippers, distributed across twelve palaces in a grid system marked by the twelve branches, producing a unique map of your life. The natural question is: how does the chart actually get built?
In the classical tradition, charting was done by hand, memorizing rules, converting dates, placing stars step by step.
I’m going to be direct about something: I don’t think beginners should spend much time learning to chart by hand. Many traditional teachers will disagree. But reliable charting tools exist now, and the calculations are mechanical. Spending weeks memorizing placement formulas is time better spent understanding what the placements mean. More importantly, there are some subtle, potentially controversial, points about how to generate a chart, which I believe deserve more attention than the general calculation methods.
For generating your chart, use our tool at polarastrology.com/chart. Enter your birth data, get your chart instantly. The rest of this lesson covers what you need to know to use that tool well, the inputs it expects, the adjustments it makes to your birth time, and a question about the day boundary that affects readers in the Americas.
The Inputs
A Polar Astrology chart needs a few things from you:
Birth year, birth month, birth day, enter these as you’d normally tell someone your birthday, in the standard Gregorian calendar. Under the hood, the charting tool converts everything to the Taoist/Chinese lunar calendar to derive the information needed for calculation. You don’t need to do any conversion yourself.
Birth time, enter the time on your birth certificate.
Birth location, enter where you were born. The tool uses this to calculate your true solar time, adjusting for daylight saving time (if applicable) and for the difference between your clock time and the actual solar time at your longitude. More on why this matters below.
Under the Hood:From these inputs, the charting tool calculates a Five Elements Bureau (五行局), places Polaris, cascades all fourteen major stars into position, assigns auxiliary stars, and determines your luminosity values and transformations. The mechanics, bureau calculation, Polaris placement formulas, cascade rules, are all taken care of by our software. For reading your chart, you don’t need them.
True Solar Time: What the Tool Is Doing
Polar Astrology works in two-hour blocks (時辰, shíchén). Whether you were born at 3:15 AM or 4:45 AM, same block, same chart. But which block you actually belong to depends on the solar time at the place you were born, not the clock time on your birth certificate.
The charting tool handles this conversion automatically when you enter your birth location. But it’s worth understanding what’s happening under the hood, because it affects which chart you get. Here are a few common reasons why true solar time differs from your clock time.
Daylight Saving Time
If you were born during daylight saving time (summer time), your birth certificate records clock time, which is one hour ahead of standard time. That hour can easily push you across a block boundary.
For example: a birth certificate says 7:15 PM EDT (Eastern Daylight Time). The actual standard time is 6:15 PM EST. That’s You Hour (5:00–7:00 PM). If you used the clock time directly, 7:15 PM would fall in Xu Hour (7:00–9:00 PM), the wrong period, the wrong chart.
DST rules have changed throughout history and vary by location, they’re not something you should try to guess. The charting tool looks up the correct DST status for your birth city and date automatically.
Longitude Correction
This is subtler but can matter. Each timezone is based on a standard meridian (for example, 90°W for US Central Time). If your birth city is significantly east or west of that meridian, the local solar time differs from the clock time by several minutes.
The correction is four minutes per degree of longitude. If your city is east of the standard meridian, add time. If west, subtract.
A practical example: Houston, Texas is at longitude 95.4°W. The Central Time standard meridian is 90°W. Houston is 5.4° west, so local solar time is about 22 minutes behind clock time. A birth recorded at 9:47 PM CDT in Houston becomes:
- Subtract 1 hour for DST → 8:47 PM CST
- Subtract 22 minutes for longitude → 8:25 PM true solar time
- 8:25 PM = Xu Hour (7:00–9:00 PM)
Without the corrections, 9:47 PM would fall in Hai Hour (9:00–11:00 PM), wrong period, wrong chart.
Again, the tool handles this for you. But if your birth time falls near a block boundary, it’s worth checking the true solar time the tool calculated and understanding why it differs from your clock time.
When It Doesn’t Matter
If your birth time falls solidly in the middle of a two-hour period, say, 2:30 PM, right in the center of Wei Hour (1:00–3:00 PM), no reasonable correction will shift you into a different period. Don’t worry about it.
The corrections matter when your birth time is within about 30 minutes of a period boundary. In those cases, you might want to generate charts for both possible periods and compare which one fits your life better. The right chart is usually obvious.
Local Lunation
While classical Western astrology understands the importance of lunations, it is common for chart reading to only glance over them. Polar Astrology, on the other hand, bakes the lunation into the core charting algorithm. This is arguably one of the key strengths of Polar Astrology.
Local Lunation is a setting on polarastrology.com/chart that is enabled by default. It reflects my own view, I have not seen it discussed elsewhere or implemented in mainstream software, but I believe it is grounded in first principles. Let me explain.
The Five Elements Bureau is a key calculation in charting: it determines where Polaris lands, which in turn cascades the positions of all the other major stars. The bureau is derived from the Heavenly Stem of your birth year combined with your lunar birth month. The lunar month, in turn, is defined by lunation, the cycle of new moons.
Here’s the problem that most people don’t realize: many charting tools determine the lunar month directly from the traditional Chinese lunar calendar, which is based on Beijing time. For someone born in China, this is generally appropriate. But for someone born in the Western Hemisphere, where the time difference from Beijing can be twelve hours or more, a new moon that falls on one day in Beijing may fall on a different day locally. When that happens, the lunar month boundary shifts. If your charting method depends on the local lunation rather than the Beijing calendar, that difference can produce a different Five Elements Bureau, which in turn changes the placement of Polaris and the rest of the chart.
Our tool calculates the lunation for your actual birth location rather than defaulting to Beijing time. Later in the case studies, we’ll see Steve Jobs’s chart as a striking example: the local lunation method produces a chart whose placements correspond much more closely to his biography than the Beijing-based lunation method.
The Zi Hour Problem: Births Between 11 PM and 1 AM
There’s an old saying in Polar Astrology: “Even deities find it hard to judge a Zi hour chart” (神仙难断子时命).1 If you were born between 11:00 PM and 1:00 AM, you fall within the Zi hour (子時), and this creates a unique complication worth understanding.
The Zi hour spans midnight. That means it straddles the boundary where one calendar day ends and the next begins. A person born at 11:30 PM on March 15 and a person born at 12:30 AM on March 16 are both in the Zi hour, same two-hour block, same Life Palace position. But which day should the chart use? The one that’s ending or the one that’s beginning?
Different schools answer this question differently, and the debate has continued for centuries, which is presumably why the ancients warned that even immortals struggle with it. I won’t go into the technical details of the competing approaches here, because I believe that, in practice, other factors often matter more than the theoretical choice. The equation of time changes from day to day, so a true solar day is not exactly twenty-four hours. In addition, because the Zi hour straddles midnight, even a small uncertainty in the recorded birth time can change the calendar-day assignment.
My recommendation is simple: if your true solar birth time falls within the Zi hour, generate both possible charts and compare them against your life.
To do this, first generate your chart at polarastrology.com/chart and note the true solar time shown on the results page. If the true solar time falls between 11:00 PM and 1:00 AM, create a second chart by shifting the input birth time just enough to move the true solar time to the opposite side of midnight. You will then have two charts representing the two possible calendar-day assignments for the same Zi hour. Compare both against your own life and see which one fits more convincingly. Don’t agonize over the theory, let your biography settle the question.
For Readers in the Americas: The Atlantic Date Line
If you’re generating a chart from the Western hemisphere, there’s one more adjustment to consider. This one is more speculative than the timezone corrections, but I’ve tested it against real charts and I think it’s worth taking seriously.
The Chinese Gan Zhi day cycle, the sixty-day cycle of Heavenly Stems and Earthly Branches, has been running continuously for thousands of years, anchored to China. In East Asia, the question of when one day ends and the next begins is simple: midnight, local time. But what about someone born in the Americas?
The International Date Line runs through the Pacific Ocean. Cross it heading east, and you go back a day. This is a convention established for global navigation, invented in the 19th century for the convenience of European shipping. The Gan Zhi cycle predates it by millennia. And there’s a case to be made that it’s the wrong boundary.
Here’s the argument. If you think about the Gan Zhi day as radiating outward from China in both directions, the natural place where the cycle “resets”, where the day boundary falls, would be on the opposite side of the globe from China. That’s not the Pacific. That’s the Atlantic.
This isn’t just abstract geometry. It has a historical and anthropological logic. The Pacific Ocean was not a barrier to human civilization, it was a bridge. The ancestors of Native Americans crossed from Asia to the Americas via the Bering land bridge and coastal migration routes, tens of thousands of years before anyone crossed the Atlantic. If the Gan Zhi cycle traveled with human civilization as it spread eastward from China, through Central Asia, through Siberia, across the Pacific rim, and into the Americas, it would have crossed the Pacific without interruption. The natural boundary, the place where the continuous chain of eastward migration finally hit open ocean it couldn’t cross, was the Atlantic.
The practical consequence: for someone born in the Americas, the Gan Zhi day may be one day ahead of their local calendar date. The charting tool shows this as the “Adjusted day for Americas” option.
I started with this as a theoretical position. Then I tested it. I ran both the standard and adjusted-day charts for several well-known Americans whose birth data is documented from birth certificates, and compared which version better matched their known biographies. The adjusted method won in most cases. I’m not claiming this is settled. But the pattern is suggestive enough that I recommend trying the adjusted option for anyone born in the Americas, while always generating both versions to compare.
Other Sensitive Edge Cases
So are the above all edge cases that one needs to be very careful about? Well, not exactly. There are still other types, but we won’t go into too many details. In general, as long as you get the birth date correct, the complexity should be taken care of by our charting tool at polarastrology.com/chart, so we won’t bore the readers with additional technical discussions. Also, the remaining categories only affect a very small percentage of charts. For example, charts very close to certain solar ingress times might have accuracy issues (if the sun is very close to 15 degrees of Aquarius, which is when the traditional Taoist/Chinese calendar changes the solar year; and there also exist minor schools that calculate charts slightly differently around this time). Again, if you get the birth time and location exactly right, it should be correct. But if you have any doubts, this could be the time to talk to an experienced practitioner of Polar Astrology to rectify your chart.
- The saying 神仙难断子时命 (“Even immortals find it hard to judge a Zi hour chart”) is widely cited in Chinese astrology texts. The Yuanhai Ziping (渊海子平) addresses the early/late Zi hour distinction: “The Zi hour divides into front and back, the front belongs to yin darkness, the back belongs to yang brightness” (子时分前后，前属阴晦，后属阳明). The Sanming Tonghui(三命通会) similarly notes: “Zi divides into yin and yang, the front belongs to yin, the back belongs to yang” (子分阴阳，前属阴而后属阳).