Gregorian adoption and continuing lunar observance in China

The republican change

The Republic of China adopted Gregorian civil dating with January 1, 1912 as the first day of its first year. Sun Zhongshan, widely known in English as Sun Yat-sen, issued his telegram announcing the change on January 2. The reform introduced both a new civil calendar and a new system of year numbering, beginning with republican year 1.

Early publication policy allowed the two calendars to appear together. A January 1912 directive provided for weekdays alongside Gregorian dates and solar terms alongside the traditional calendar. Selected customary information could remain, while auspicious and inauspicious classifications and associated divinatory material were to be removed. The government was changing the contents of the familiar almanac as well as the way official dates were written.

Dual dating also helped people use the new system. A February 1912 circular required government documents to carry both Gregorian and lunar dates. Officials could introduce the new civil calendar while making its dates recognizable to readers accustomed to the older one. Adoption as government policy and replacement in everyday practice were separate processes.

Two New Years and everyday use

Gregorian January 1 provided the civil year boundary. The first day of lunar month 1 remained the traditional Chinese New Year, celebrated as Spring Festival. Lantern Festival continued on lunar month 1, day 15, and Mid-Autumn on lunar month 8, day 15. Their Gregorian dates change from year to year because they follow lunar months.

For republican reformers, the calendar was part of a wider effort to reorganize public life. A common civil calendar could coordinate government business, schools, commercial records and public commemorations. Moving traditional holidays onto Gregorian dates, however, affected established patterns of family reunion, worship and seasonal celebration. Changing the date written on a document was easier than replacing the annual sequence around which households organized these activities.

Nationalist policy became more restrictive in 1929. A July order prohibited the continued publication of parallel Gregorian and lunar calendars from 1930. An October order required business accounts, contracts and other civil and commercial documents to use republican Gregorian dating without additional lunar dates. These measures targeted publishers and documentary practice, as well as the public use of the older calendar.

Traditional holidays nevertheless continued to be observed. The coexistence of calendars offered a practical arrangement: Gregorian dates organized official and working schedules, while lunar dates located festivals and family observances. Printed calendars could place a large civil date beside a smaller lunar date, letting readers move between these uses on the same page.

The traditional calendar's structure also helped preserve its seasonal role. It was lunisolar, with leap months keeping lunar months aligned with the seasonal year. Retaining lunar festival dates therefore did not mean allowing those festivals to drift indefinitely through all four seasons.

Year numbering and month dates

Changing the number of the year is different from changing the calculation of its months. Republican, or Minguo, year numbering begins with 1912 as year 1. For a positive republican year number, add 1911 to obtain the corresponding Gregorian year.

These are year correspondences, not conversions of lunar months and days. An official republican Gregorian date uses Gregorian month lengths and January 1 as the year boundary. An informal family record can use a republican year label with a lunar month and day. In that case, the lunar date still needs conversion, and a late lunar month can extend into the following Gregorian year. Wording such as “old calendar,” paired dates and the document's context help identify the intended system.

In September 1949, the Chinese People's Political Consultative Conference adopted Common Era year numbering for the People's Republic, specifying that the current year was 1949. This replaced republican year numbering in that state's official dating. Gregorian month lengths and the January 1 civil year boundary had already been introduced in 1912.