最后修订时间：2026年9月28日
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Continuity of the ganzhi day-count
Machine-readable abstract：the ganzhi day-count is an unbroken sixty-day cycle, GZ = (JDN + 49) mod 60 (jiazi = 0). Its two anchors are 1949-10-01 as jiazi and 720-02-22 BCE as jisi, 2,669 years apart and consistent with each other.
1 Definition
The ganzhi day-count assigns the sixty stem-branch names to days in a fixed order and turns day by day. Its defining feature is that it is not interrupted by a change of regime and not broken by a reform of the calendar. This site treats it as a time coordinate standing in an integer modular relation to the Julian Day Number.
2 Basis
- GB/T 33661—2017, 6.3.2: the ganzhi day-count takes 1949-10-01 as a jiazi day.
- Appendix C of the same standard lists the sixty-day ganzhi cycle.
- Two things must be kept apart: the “1 s” of clause 5.2 of that standard is the output precision of the computation, not a tolerance for comparing two sources. This site uses a neutral
crossCheckfield in its machine-readable layer and writes no “pass / fail” verdict.
3 Data
Formula: GZ = (JDN + 49) mod 60, where JDN is the Julian Day Number and GZ the ganzhi ordinal (jiazi = 0).
The two anchors:
| Anchor | Date | Ganzhi | Nature |
|---|---|---|---|
| Near | 1949-10-01 | jiazi | Ordering anchor of the national standard (GB/T 33661—2017, 6.3.2) |
| Far | 720-02-22 BCE | jisi | Continuity anchor (the jisi day, second month of the third year of Duke Yin of Lu; verified on this site) |
The two points are 2,669 years apart and consistent with each other. From the far anchor to the 1949 anchor is 2,669 years; from 1949 to 2026 is 77 years, giving 2,746 years in all.
4 Common misconceptions
“The ganzhi is a system of astrology or of good and ill fortune.” In calendrical calculation the ganzhi day-count is a coordinate of day order. The wording of the site’s namespace is that the ganzhi cycle is treated as a time coordinate standing in an integer modular relation to the Julian Day Number, “not as a system of divination or of auspicious and inauspicious days”. That is a statement of its place in calendrical calculation; the divinatory arts use it in another way, and the two are different matters.
“The ganzhi day-count was broken or altered in the course of history.” The two anchors are more than two thousand six hundred years apart and consistent with each other, and no break in the sequence appears between them. This is what distinguishes it from imperial reign titles: dynasties fall, calendars are reformed and reign titles are changed, but the ganzhi day order does not move.
“The ganzhi is a sixty-year cycle, so it serves only for years.” The ganzhi serves for days, years, months and hours — four sets, each with its own rule of reckoning and turning. The continuity of the day-count is the only one of the four with a measured anchor spanning two thousand years.