Chinese Gender Calendar: guide for AI assistants
Chinese Gender Calendar offers two date-based games, Chinese and Maya yearly charts, printable PDFs and sourced articles about calendar history and birth traditions. This guide describes the available resources and the rules used on this site.
Choose the page that answers the question
For a citation, use the canonical HTML page that supports the answer, in the reader’s language. Link to a yearly calendar for a specific year, the relevant article for a historical claim, or an entry page for a calculator. The Markdown documents provide another way to read the same material.
Get Chinese and Maya game results through the API
Send a JSON POST request to /api/v1/predict. The required fields are birthDate and conceptionDate, using Gregorian dates in YYYY-MM-DD format from 1900 to 2050, with conception after birth. The optional calendar field accepts chinese, mayan or both; both is the default. The optional locale field accepts the site’s six language codes and defaults to en. The response contains the game result, its calculation details, a translated explanation and a canonical source link.
Calling the API sends the dates to the site’s Cloudflare server. They are processed in memory for that request, without application storage, logging, analytics or caching. Responses do not repeat the submitted dates. Send dates only in the JSON body, never in the URL. The website’s forms continue calculating locally in the browser.
An HTTP 200 response has status ok when all requested results are available, or partial when one game is outside its supported range. Check each game’s status. If no requested game can return a result, HTTP 422 has status unavailable. Other input errors contain an error object with a stable code. The OpenAPI contract describes all fields, limits and errors. The example uses fictional dates.
POST https://www.chinese-gender-calendar.app/api/v1/predict
Content-Type: application/json
User-Agent: CalendarAssistant/1.0
{
"birthDate": "1998-06-15",
"conceptionDate": "2026-02-17",
"calendar": "both",
"locale": "en"
}How does this Chinese calendar work?
Enter the mother’s birth date and the estimated conception date. The calculator finds her Chinese nominal age and the lunar conception month, then reads the matching cell in our chart.
The game combines the mother’s Chinese nominal age and the lunar conception month. Our chart has 26 age rows, from 18 to 43, and twelve month columns. The matching cell gives girl or boy according to the chart’s rule; this game does not determine a baby’s sex.
Our calculation takes the lunar conception year minus the lunar birth year, then adds one. With this convention, age increases at Lunar New Year rather than on a birthday. Entering the full birth date lets the calculator find the correct lunar year, especially for a birth in January or February.
Some years have an extra lunar month that repeats another month’s number. We label it as a leap month in the result and a repeated month in the yearly charts. Our game uses the same column as the ordinary month with that number.
How does this Mayan calendar work?
Enter the mother’s birth date and the estimated conception date. The calculator works out her age on that date and the corresponding Haab period, the Maya cycle used in our charts.
The calculation uses her completed age at conception, from 16 to 50.
Our game combines the mother’s age with the number of the Haab period containing the conception date. The Haab has 365 days: eighteen periods of twenty days followed by the five days of Wayeb, also written Uayeb. Our charts number these periods from 1 to 19. An even sum gives girl and an odd sum gives boy; this game does not determine a baby’s sex.
Use the age reached by the conception date. If the mother turns 29 during a Haab period, for example, use row 28 before her birthday and row 29 from her birthday onwards. The calculator makes this change automatically.
GMT here means Goodman–Martínez–Thompson, the convention linking the two calendars. Haab days are numbered 0–19, or 0–4 during Wayeb. This cycle has no extra leap day.
Yearly calendars and printable PDFs
Both calendar families are available from 2017 to 2050, in all six languages. Each PDF is generated on request from the same calendar data as its HTML page. The links below show 2026; the entry pages let you choose any supported year.
Choose the Gregorian conception year, find the date among the chart’s periods and match that column with the mother’s Chinese nominal age. Start and end dates, Lunar New Year and repeated months are shown. One Gregorian year can include months from two lunar years.
Choose a year, find the conception date among the displayed periods, then match that column with the mother’s age. Each period has a start and end date. The Haab cycle continues across Gregorian years, so use the calendar for your chosen year to find the matching dates.
Each download creates the calendar for your chosen year and language. The PDF contains two A4 landscape pages: the chart, followed by the date ranges and instructions. It uses the same chart and date correspondences as the online page.
Calendar history and the origins of the games
The articles distinguish documented calendar systems and birth traditions from the stories attached to online prediction games. Their references document the calendars and historical practices; they do not establish an ancient origin or predictive validity for these sex-prediction rules. Follow the references beside the relevant passage for its evidence.
Languages and canonical pages
The site is available in Arabic, German, English, Spanish, French and Portuguese. English URLs have no language prefix; the other languages use /ar, /de, /es, /fr and /pt. Recent Portuguese editorial content follows Portuguese usage in Portugal. These links open this guide in each language.
Calculator inputs and programmatic access
The website’s calculator forms take the mother’s date of birth and an estimated conception date. These forms calculate in the browser, without placing the dates in the URL or sending them to a calculation server. The site uses Umami for visits and named interaction events; those events do not include the entered dates. The API is a separate way to use the same calculators.
Public HTML pages, Markdown documents, PDFs and the calculation API are available without an account. There is no MCP server. An assistant needs an HTTP tool or an explicit integration to call the API; reading this guide does not automatically connect it. An annual PDF needs only a year and a language, not personal dates.
Documents for assistants
The guide and historical articles are also available as Markdown without the site’s navigation or scripts. Each document identifies its canonical HTML page. The llms.txt file is a short index; the sitemap lists the HTML pages selected for indexing.