Enter a Gregorian date (day and month optional) to find the corresponding Vietnamese reign period(s), lunisolar date, and sexagenary year. Multiple results indicate concurrent dynasties.
Reign year numbering: Year 1 of a reign corresponds to the CE year in which the reign began. Year N = start year + (N − 1).
Lunisolar calendar: Vietnamese documents use the lunisolar calendar. Lunar month/day conversions use the Hồ Ngọc Đức algorithm (UTC+7). Accuracy is ±1 day for dates before c. 1500 CE.
New Year offset: The Vietnamese New Year (Tết) falls in late January or early February. Dates in January–February of a CE year may belong to the previous Vietnamese lunar year.
Overlapping dynasties: During 1533–1592 the Mạc dynasty and the Later Lê restoration each issued concurrent reign names. A document's political allegiance determines which system it follows.
Intercalary months: A leap month (tháng nhuận) is added roughly every 2–3 years. Not every month number has an intercalary counterpart in a given year.
Sexagenary cycle: The 60-year cycle (lục thập hoa giáp) anchors to 4 CE (Giáp Tý). Only same-parity stem–branch pairings are valid, yielding 60 unique combinations.