Last revised: 2026-10-18
简体中文 ｜ 繁體中文 ｜ English ｜ 日本語 ｜ 한국어
Look up the Gregorian date and time, the lunar date and its four pillars, the apparent solar-time double-hour, the weekday, and the previous, current and next solar terms, for any day from 1 January 1901 to 20 November 2052. The lunar date runs from 20 January 1901; for the nineteen days before that (1–19 January 1901) the converter gives the Gregorian date, weekday, four pillars, apparent solar time and solar terms, and leaves the lunar field blank.
Everything comes from the same data used by this site’s solar-term pages, new-moon pages and dataset; no second algorithm is run. The lunar calendar takes the conjunction as the month start, the month containing the winter solstice as month 11, and intercalates between two month-11s. Solar terms fall at every 15 degrees of the Sun’s apparent longitude. The sexagenary day is the Julian day number modulo 60, with 1949-10-01 as a jiazi day. The year and month pillars of the four are bounded by the solar terms, and the lunar year of the lunar line by the first day of the first lunar month; see Scope below. The apparent solar time is corrected for the longitude of the chosen place and for the equation of time. Enter local time; every line of the result is shown in Beijing time.
The equation of time through the year
The equation of time is the difference between apparent solar time and mean solar time. The apparent solar time given above already includes it; the chart sets it out on its own, one value per day, with the twelve months across and minutes up. It has four extremes in the year: about −14.3 min on 14 February, +3.9 min on 15 May, −6.6 min on 28 July and +16.4 min on 1 November, crossing zero on 16 April, 15 June, 2 September and 26 December. The curve comes from the same NOAA approximation as the converter, within one minute of published values; the sample year is 2025 (a common year), the difference in a leap year being under a second.
Scope
Modern recomputation, not prediction. For astronomical reference only; no astrology, apocrypha or fortune interpretation.
The date and time you enter are local time: pick, in the time-zone list, the zone the chosen city keeps. All the working is done in Beijing time, and every line of the result is shown in Beijing time (mean solar time at 120 degrees east) so that the lines stay consistent. Apparent solar time = Beijing time + (longitude of the chosen place − 120) × 4 minutes + the equation of time. The equation of time uses the NOAA approximation, within one minute of published values; a positive value means apparent solar time is ahead of mean solar time, a negative value behind; one double-hour (shichen) spans two hours, the zi hour starting at 23:00. Daylight saving is not applied for you: on this page choose the standard or the daylight entry in the time-zone list that matches the date.
The four pillars are reckoned by the sexagenary calendar: the year pillar turns at the ingress of Beginning of Spring; the month pillar at the ingress of each of the twelve nodal terms (Beginning of Spring, Awakening of Insects, Clear and Bright, Beginning of Summer, Grain in Ear, Minor Heat, Beginning of Autumn, White Dew, Cold Dew, Beginning of Winter, Major Snow, Minor Cold); the day pillar from the Julian day number modulo 60; and the hour pillar from the day stem, the tzu hour opening the round. The year of the lunar line is reckoned separately, by GB/T 33661—2017, from the first day of the first lunar month. Between Beginning of Spring and that first day the two year pillars differ by one year, each after its own system.
The place list holds 361 entries in the United States, grouped under the fifty states and the District of Columbia; the default is New York City. Longitude is that of a representative point. Places on this page are United States cities; the time basis stays Beijing time, as above.
Boundary
The lunar part runs from 1901 to 20 November 2052: its lower bound is set by the preceding winter solstice, its upper bound by the ephemeris used (JPL DE421, covering to 2053-10-08). No conversion outside the date range.