Lunar Date Converter
Convert lunar ↔ solar dates accurately
What is the Vietnamese Lunar Calendar?
The Vietnamese lunar calendar (lịch âm) is a lunisolar calendar based on moon phases, combined with solar cycles to determine leap months. It is widely used in Vietnamese culture to set holidays, Tết (New Year), and auspicious dates.
Why convert between lunar and solar dates?
Converting between lunar and solar dates helps determine the exact solar date for lunar events like birthdays, death anniversaries, and Tết Nguyên Đán. Conversely, solar-to-lunar conversion tells you today's lunar date.
Lunar vs Solar Calendar Comparison
| Feature | Lunar | Solar |
|---|---|---|
| Basis | Moon cycle | Sun cycle |
| Month length | 29-30 days | 28-31 days |
| Year length | 354-355 days | 365-366 days |
| Leap month | Yes (7/19 years) | No |
Algorithm
MoonLich uses Hồ Ngọc Đức's algorithm (University of Leipzig) with 100% accuracy for the period 1900–2100. Based on Jean Meeus' "Astronomical Algorithms" (1998).
- What is the Vietnamese lunar calendar?
- The Vietnamese lunar calendar (lịch âm dương) is a lunisolar calendar based on the Moon's cycle (29.5 days/month), combined with the Sun's cycle to determine leap months. A lunar year has 354-355 days, 10-11 fewer than the solar year. Every 19 years, 7 leap months are added for synchronization.
- How to convert lunar dates to solar dates?
- MoonLich uses Hồ Ngọc Đức's algorithm (University of Leipzig) for precise conversion. Select a lunar date, and the tool automatically calculates the corresponding solar date based on astronomical calculations (Moon and Sun positions).
- What is a leap month in the lunar calendar?
- A leap month is an extra month added to the lunar calendar to synchronize with the solar year. In a 19-year cycle, 7 years have a leap month. The leap month is determined by the Sun's position (solar terms). MoonLich automatically identifies leap months.
- What's the difference between the lunar and solar calendars?
- The solar calendar is based on the Sun's cycle (365.25 days/year), with months of 28-31 days and no leap months. The lunar calendar is based on the Moon's cycle (354-355 days/year), with months of 29-30 days and leap months added 7 times every 19 years.
- How accurate is the conversion algorithm?
- MoonLich uses Dr. Hồ Ngọc Đức's algorithm (University of Leipzig, Germany) — the most widely used algorithm for the Vietnamese lunar calendar. It has 100% accuracy for the period 1900-2100, based on Jean Meeus' Astronomical Algorithms (1998).
Cập nhật: · MoonLich Team