Published · Reviewed August 21, 2026
Solar Terms or Lunar Calendar?
Learn which calendar details preserve a birth record, which boundaries Clarify currently uses for Year and Month Pillars, and how to audit a conversion without mixing calendar systems.
Also known as: BaZi calendar rules · solar terms versus lunar calendar · BaZi lunar or solar calendar · Jié Qì hái shì Nóng Lì · 节气还是农历
Plain-English answer
A BaZi calculation can receive a Gregorian date, a converted Chinese lunar date, or a historical record written in another calendar, but the input format does not automatically decide every pillar boundary. The Chinese calendar contains both moon-based months and solar terms. Clarify preserves the birth record, then applies its declared chart rules: the Year Pillar changes at the calculated Spring Commences crossing, and the Month Pillar is mapped from solar longitude into twelve positions. A lunar date remains useful provenance; it is not silently treated as the Month Pillar.
Concept overview
- English term
- Solar Terms or Lunar Calendar?
- Chinese term
- 节气还是农历
- Pinyin
- Jié Qì hái shì Nóng Lì
- Content status
- Published educational reference
The short decision table
- Recorded date
- Keep what the source actually says, including calendar type, local clock time, place, precision, and whether a lunar month is a leap month. This is the evidence layer.
- Converted civil date
- Use a documented conversion when software needs a Gregorian date. Store the original and converted value together so a later reviewer can reproduce the step.
- Year Pillar boundary
- Clarify currently compares the normalized birth instant with its calculated Spring Commences moment at the 315-degree solar-longitude crossing.
- Month Pillar boundary
- Clarify currently uses twelve solar-longitude positions beginning from the same 315-degree reference, not the first day of a Gregorian or lunar month.
- Interpretation
- Calendar processing calculates chart labels under a method. It does not establish personality, moral character, relationship outcomes, health, wealth, or future events.
Three calendar layers that should not be collapsed
First is the source record: the date and clock notation written by a parent, hospital, registry, family book, or other record. Second is representation: the same date may be expressed in Gregorian or Chinese calendar terms after conversion. Third is the pillar method: a calculator chooses specific boundaries for the Year, Month, Day, and Hour Pillars. These layers can interact, but they are not interchangeable.
The Hong Kong Observatory explains that Chinese calendar months follow moon phases while the 24 solar terms mark positions along the Sun's apparent path. It also explains why leap lunar months exist. That astronomy supports the distinction between a lunar-month label and a solar-term moment; it does not decide every BaZi school question. Clarify must therefore state its own implementation rather than present one convention as a law of nature.
What Clarify currently does
- Normalize time when a city is known
- The full chart path resolves the city's IANA time zone for the recorded date. When longitude is available, it also calculates a solar-time correction for the hour and timing layer.
- Find the Year Pillar interval
- The engine calculates the 315-degree Spring Commences crossing and tests whether the birth instant is before or after it.
- Find the Month Pillar position
- The engine calculates solar longitude at the reference instant and maps the angle from 315 degrees into one of twelve 30-degree positions.
- Keep the civil-date identity rule visible
- Clarify deliberately keeps the Day Pillar on the recorded civil date so the free identity card and full report do not change identity because a solar correction crosses midnight.
- Render structured results
- Any personal pillars or Chinese characters must come from deterministic structured output. A visual layer may format verified fields; an image model must not invent or repair them.
Run a Date Representation Check
- 1. Copy the source Record the date exactly as supplied. Mark the calendar, language, precision, and source rather than converting it in place.
- 2. Resolve missing calendar state For a Chinese lunar date, confirm year, month, day, and leap-month status. An unlabeled month number is not enough for a reproducible conversion.
- 3. Record the conversion Save the converted Gregorian date, conversion source or library version, and reviewer. Do not erase the original notation.
- 4. Add time and place Attach the recorded local clock time, time-known state, city, country or region, and resolved time zone. Calendar conversion alone does not identify an instant.
- 5. State pillar rules Name the Year, Month, Day, and Hour conventions used by the target calculator. If two methods are compared, generate two labeled records instead of mixing fields.
- 6. Preserve uncertainty If the record cannot distinguish a leap month, exact time, or boundary side, keep that uncertainty visible and avoid presenting one personal chart as certain.
Worked record without inventing a personal chart
- Original evidence
- Chinese calendar year, month, day; evening; city and region; leap-month state not yet verified.
- Conversion state
- Pending. No Gregorian date is accepted until the leap-month state and conversion authority are recorded.
- Time state
- Unknown within an evening range. The Hour Pillar must not be fabricated from a guessed minute.
- Boundary state
- Year and Month boundaries cannot be tested until the converted date, place, and sufficient time precision are available.
- Allowed conclusion
- The record needs clarification. It does not support a final chart, a personality label, or a future-oriented reading.
If another calculator disagrees
A disagreement is not resolved by choosing the result that feels more accurate. Compare the original input, calendar conversion, leap-month flag, time zone, solar-time setting, Year boundary, Month boundary, Day boundary, hour division, and calculation version. One changed field may propagate through several derived labels. Keep each complete result under its own method name and timestamp.
If the birth is far from every relevant boundary, two methods may still agree. If it is close, a small correction can change a pillar. That is a data-quality and method-sensitivity issue, not evidence that one chart has found a hidden event.
Common mistakes
- Using Lunar New Year as every year boundary
- Lunar New Year and Spring Commences can fall on different dates. Record which convention the calculator uses.
- Calling the lunar month the Month Pillar
- A lunar month label and Clarify's solar-longitude Month Pillar position are different fields.
- Treating February 4 as a whole-day switch
- Spring Commences is an astronomical moment whose local clock display depends on time zone and year.
- Dropping the original date after conversion
- A converted value without its source calendar, leap-month state, and conversion version cannot be independently audited.
- Letting a generated image fill chart text
- Personal chart characters are calculation outputs. Missing or uncertain input must remain missing or uncertain.
Frequently asked questions
- Is BaZi a lunar-calendar system?
- That shorthand is incomplete. Chinese calendrical practice includes lunar months and solar terms; Clarify's Year and Month Pillars use declared solar-term rules.
- Can I enter a lunar birth date?
- Only through a conversion flow that preserves calendar type, leap-month state, original value, and conversion version. The current product form should be followed as displayed.
- Does a correct conversion guarantee a correct reading?
- No. It supports the calculation layer. Interpretation remains traditional, conditional, and limited by the full chart, method, evidence, and product boundaries.
- What if my birth time is unknown?
- Record it as unknown. Do not invent an Hour Pillar. Use the existing birth-time Guide for what can and cannot be done without it.
Calculation is not destiny
A date representation, solar term, boundary flag, or pillar is not a diagnosis or factual prediction. Treat BaZi as a traditional reflection framework. It must not replace medical, legal, financial, mental-health, safety, or other qualified advice, and it must not be used to decide another person's rights or opportunities.
Where to go next
- Li Chun Year Boundary
- Audit the exact Year Pillar switch and a birth close to Spring Commences.
- Solar-Term Month Boundaries
- See the twelve month positions and run a Month Pillar boundary check.
- Time Zones
- Resolve a recorded local clock time before comparing it with a boundary.
Use with Clarify
Free BaZi Reading
Apply reviewed concepts only after Clarify calculates a complete chart.
Sources & editorial basis
- Clarify editorial sourceSupporting source recorded in the Claim Ledger.
- Clarify editorial sourceSupporting source recorded in the Claim Ledger.
- Clarify deterministic chart systemCurrent product implementation and tests; supports Clarify behaviour only.
- Clarify MethodologyCurrent calculation and editorial workflow; product-behaviour source.
- Clarify published BaZi guidesReviewed public guides used for terminology and learning-order continuity.
- Clarify DisclaimerCurrent product boundaries for interpretation and consequential decisions.
Source-to-claim locators are maintained in Clarify's editorial evidence record.