BaZi Chart FAQ: time, boundaries, and what we calculate
Facts stay free. Readings are one-time. The questions below are the rules the calculator already uses.
Getting a free chart
Do I need an account to see my BaZi chart?
No. The Four Pillars calculator is free and does not require sign-up. Nothing from a free calculation is saved as a permanent chart on our servers. Google sign-in is required only if you buy a one-time PDF report, or if you claim the one short reading on a result page.
Is the free chart the same as a paid report?
No. The free page shows chart facts: pillars, hidden stems, Ten Gods labels, element counts, Day Master strength by our published method, and a calculation receipt. Paid reports are one-time PDFs that write those facts chapter by chapter. Buying does not recalculate a different set of pillars.
Do you offer a monthly subscription for the natal chart?
No. Reports on this site are one-time PDF purchases (Essential Natal $19, Complete Natal + 10-Year Luck $29, Compatibility $19, 2027 Annual Forecast $24 — prices as listed on pricing). There is no chart subscription as the default product.
True solar time (TST)
What is true solar time in BaZi?
True solar time adjusts civil clock time for the Sun’s real position at the birthplace: longitude relative to the time-zone meridian, the equation of time, and daylight saving removed. BaZi double-hours follow the Sun, not the wall clock alone. Details: true solar time.
Do you use true solar time by default?
Yes, whenever you give a birthplace. You can turn it off. TST only changes the chart when the correction crosses a double-hour boundary or the day-change line (default 23:00).
What if I do not know the birth city?
Without a city we cannot apply the full TST correction. The calculator uses clock time and marks that on the receipt. Prefer the city of birth (or the hospital city) when you know it.
Will true solar time always change my hour pillar?
No. Many births stay in the same double-hour after correction. The receipt shows the correction size so you can see whether a boundary was crossed.
Daylight saving (DST)
Do you leave daylight saving in the birth time?
No. For TST we remove daylight saving so the solar correction is not skewed by a seasonal clock shift. Civil DST is a legal clock change; the solar equation is separate.
I was born during DST. Which time should I type?
Type the civil clock time on the birth record (what the hospital wrote), and select the correct city/date so the engine can undo DST as part of true solar time. Do not manually subtract an hour unless you are deliberately experimenting with the TST off switch.
Can DST alone flip my day pillar?
It can, when the civil clock sits near the day-change line and the DST/TST stack moves the solar instant across that line. Check the receipt and the boundary callout on the result page.
Zi hour / day boundary
Does the BaZi day start at 23:00 or midnight?
Schools disagree. This site’s default day change is 23:00 local (early Zi). You can switch to midnight. The hour pillar still uses the twelve double-hours. Guide: Zi-hour day boundary.
Why does 23:00 matter?
Zi (子) traditionally covers roughly 23:00–01:00. Some methods treat 23:00–00:00 as belonging to the next civil date’s day stem. If you were born in that window, flipping 23:00 vs midnight can change the day pillar and therefore the Day Master.
Which should I choose if my master uses midnight?
Use the midnight switch so your chart matches that convention, then compare. We show the rule on the receipt; we do not hide the fork.
Li Chun and year / month boundaries
Does the BaZi year start at Chinese New Year or Li Chun?
On this site the BaZi year pillar changes at Li Chun (the Sun at 315° ecliptic longitude), not at Lunar New Year. Lunar New Year matters for festivals and folk zodiac labels; it is not our year-pillar boundary. Guide: Li Chun and the BaZi year.
When do month pillars change?
At the twelve jie solar terms (节), from the Sun’s longitude — not at calendar month starts.
I was born in early February. Which year pillar do I get?
Open the receipt. Births near Li Chun sit on a documented boundary; the page shows which side you fall on under our engine.
Algorithm boundaries and cross-calculator differences
Why do two BaZi calculators give me different charts?
Usually different conventions, not bad arithmetic. Common forks: year at Chinese New Year vs Li Chun; day at midnight vs 23:00; clock time vs true solar time; DST left in vs removed. Compare receipts and switches before assuming one site is wrong.
What engine do you use?
bazi-lichun-jieqi-tst-v1. Solar-term instants use Astronomy Engine 2.1.19. Accepted birth years: 1800–2100. Place search uses GeoNames (CC BY 4.0). Full rules: methodology.
Do you guess an hour if time is unknown?
No. Unknown time means three pillars (year, month, day). Day Master still comes from the day pillar. Only births near 23:00/midnight could be ambiguous for the day stem — we do not invent a noon chart.
Is Day Master strength the same as a professional reading?
No. It is one transparent point method on this site. It omits many classical structures. Readers may weigh the same chart differently. Favourable-element (喜用神) advice is off in our paid reports at present.
Do you calculate Flying Stars on the chart page?
No. Flying Stars / Xuan Kong is a separate feng shui timing system (often tied to house facing). This calculator is natal Four Pillars only. We publish an education page on Flying Stars. We do not ship a Flying Stars engine.
Paid PDF / one-time pay
What do I get if I pay?
A downloadable PDF for the SKU you choose (natal chapters, natal + luck pillars, compatibility, or 2027 annual — see pricing). Delivery is instant after Stripe checkout. Packs are one-time; credits do not apply.
Will a paid report change my pillars?
No. Chapters are written against the same engine facts shown on the free result.
Next step: Calculate my chart. No sign-up for the chart.