Method
The chart is arithmetic. Here is all of it.
Every Truenoon reading starts from a chart that is computed, not intuited. This page walks through each step with a real example — the same one used across the site — so you can see exactly what happens to your birth data before a single sentence is written.
Working example: born August 15, 1992 at 09:12 in London.
1 · The place becomes coordinates
The birth city is matched against an offline world-cities index — the lookup never leaves Truenoon's servers. From it we take three things: latitude, longitude, and the historical timezone rules for that location, including daylight saving time as it applied on that date.
2 · The clock is corrected to the sun
Traditional BaZi divides the day by where the sun actually stands, not by administrative clock zones. So the recorded clock time is corrected in two measured steps — the longitude offset from the timezone's reference meridian, and the equation of time (the sun runs fast or slow across the year by up to ±16 minutes).
3 · Four pillars are looked up, not chosen
With the corrected moment fixed, each pillar is a deterministic calendar lookup. The year and month boundaries follow the solar terms — not New Year's Day and not the lunar new year. The day pillar comes from an unbroken sixty-day cycle that has been running for millennia. The hour pillar maps the corrected time into one of twelve two-hour bands.
4 · Da Yun is direction plus arithmetic
The decade phases are calculated too: the year stem's polarity combined with birth sex sets the direction (forward or reverse through the calendar), and the distance to the nearest solar term sets the starting age. Nothing here is interpretive — two calculators given the same input will agree to the day.
- Recorded clock time
- 09:12
- Timezone that day
- Europe/London · UTC+1
- Longitude correction
- -61 min
- Equation of time
- -4 min
- Total correction
- -64 min
- Time used for the chart
- 1992-08-15 · 08:08
These numbers are computed live by the same engine that builds paid charts — not copied into this page by hand.
What if the birth time is unknown?
The chart continues without the hour pillar rather than guessing one. The day, month, and year pillars remain exact; the report is generated at reduced precision and says so plainly wherever the missing hour matters. We consider an honest three-pillar chart more useful than a confident fiction.
Where the arithmetic ends
Everything above is reproducible calculation. The written chapters are generated on top of these computed facts — the model is never asked to invent chart data, and automated gates reject any draft that contradicts the calculated pillars, elements, or phases. The boundary is strict: arithmetic decides the chart; language only explains it.