01 · Date conversion
Official calendar references
The Hong Kong Observatory publishes English-language calendar material that lets readers compare Gregorian dates, Chinese lunar dates, and the seasonal structure of the traditional calendar.
| Reference | What it covers | Useful for |
|---|---|---|
| Hong Kong Observatory Gregorian-Lunar Calendar Conversion Tables | Annual Gregorian–lunar conversion tables for 1901-2100. | Looking up Chinese lunar years, months, leap months, days, and festival dates. |
| Hong Kong Observatory calendar guide | The Chinese Agricultural Calendar, conversion tables, and related time references. | Seeing how the annual tables fit within the Observatory’s wider calendar material. |
02 · Seasonal calendar
The twenty-four solar terms
The Hong Kong Observatory’s guide to the twenty-four solar terms explains how the terms divide the Sun’s path into 24 equal sections and how major terms relate to lunar months and leap months.
Its annual solar-term table gives the dates and Hong Kong times for each term.
The National Committee for Terms in Sciences and Technologies’ 2024 agronomy terminology consultation draft pairs the traditional 72 pentads with English terminology. The China Agricultural Museum’s introduction describes the solar terms’ agricultural history and three-pentad structure.
03 · Cultural references
Festival observances
- Chinese New YearUNESCO Intangible Cultural Heritage
- Lantern FestivalShanghai Municipal Government
- Qingming FestivalState Council Information Office
- Dragon Boat FestivalUNESCO Intangible Cultural Heritage
- QixiChina Intangible Cultural Heritage Museum
- Ghost FestivalHong Kong Intangible Cultural Heritage Inventory
- Mid-Autumn FestivalSingapore National Heritage Board
- Double Ninth FestivalHong Kong Yearbook
- Laba FestivalShanghai Municipal Government
- Lunar New Year's EveUNESCO Intangible Cultural Heritage
- Winter SolsticeShanghai Municipal Government
Calendar labels & historical interpretations
Animals and their branch relationships
The Hong Kong Observatory documents the twelve-animal cycle and the branch double-hours. Fixed elemental correspondences and relationship groups belong to traditional interpretation. Historical texts document those traditions; they are not evidence that a pair predicts a personal relationship or an event’s outcome.
The compatibility lookup covers only Six Harmonies, three-harmony groups, seasonal meetings and Six Clashes. It reports all matching categories, and does not treat two members of a three-branch group as a complete triple. Its data and English explanations are maintained within this site.
Five Phases and named relationships
Elements, Ten Gods and almanac classifications
Wu Xing Da Yi, volume 2 describes generating and controlling relationships and historical seasonal arrangements. This calendar’s branch correspondence assigns Earth to Dragon, Goat, Dog and Ox—the last branch month of each season.
San Ming Tong Hui, volume 5 explains the relationship names from the day stem: what generates it, what it generates, what controls it and what it controls. Yuan Hai Zi Ping also records the peer relationships.
Ten Gods uses the entered civil date’s day stem with a midnight boundary. Almanac day gods instead follow the day and solar-month branches; the Blessing direction uses the second Fu Shen convention. These distinct readings appear on the Ten Gods and almanac gods reference pages.
Traditional chart · calculation & evidence
Which baby chart is used?
The baby tool transcribes the 28-by-12 chart published by Allen Tsai, Chinese Fortune Calendar, updated 10 July 2025. Rows cover nominal lunar ages 18–45 and columns cover lunar months 1–12. A “B” cell is shown as Boy and a blank cell as Girl, following the publisher’s key. This is one named modern published version, not an authenticated imperial artifact.
Nominal lunar age is the conception lunar year minus the birth lunar year plus one. The conception month comes from date conversion. The published table gives no explicit leap-month rule, so this tool returns no chart label for a leap conception month, or an age outside its rows. Other charts may use different cells or conventions.
Villamor and colleagues’ population study of 2,840,755 births (2010) found that the Chinese lunar-calendar method did not predict fetal sex better than chance. A Boy or Girl cell is a folklore label, not a medical result or a prediction of a child’s gender identity.
A baby’s zodiac comes from its separately entered birth date, or an explicitly marked expected-date preview. It is not inferred from conception or from the chart cell. Parent comparisons use the corresponding birth-year branches. Changing an expected date across Chinese New Year can change the previewed animal and element.
Almanac implementation reference
The thirteen civil-day hour segments
The hour-god labels follow the lunar-javascript author’s hourly calendar documentation and its LunarTime reference. Early and late Zi are separate objects, preserving the 23:00 change in the hourly cycle. English god names use the same glossary as the daily almanac.
04 · Further reading
Using the references
The official conversion tables are the clearest place to compare a particular Gregorian and lunar date. The solar-term pages explain the seasonal framework behind the lunisolar year. Festival customs and almanac interpretations can vary by region even when the calendar date agrees.
Read the site’s calendar conventions · Festival dates and sources · Report a date or source issue
Moon & sky references
Phases and lunar mansions
NASA’s Moon phase guide explains the eight appearances and the sunlight geometry behind them. The site’s phase dates use published astronomical calculations, with a fixed UTC+8 display convention. The event-time dataset has not yet been independently checked against a separate official phase-time catalogue.
The Hong Kong Space Museum’s Chinese star glossary supplies astronomical context for the mansion names and four directional groups. The almanac’s daily mansion sequence is treated separately from an actual sky-position calculation.
Festival meaning & regional customs