How the lunar calendar is built
This is a lunisolar calendar: each month starts on the local day of a new moon and lasts 29 or 30 days. The month containing the winter solstice is month 11. A year has 12 months, or 13 when a leap month is added, about seven times in 19 years.
When 13 months fall between two winter-solstice months, the first month without a major solar term repeats the preceding month’s number. The tool shows a leap second month in 2023 and a leap sixth month in 2025, from 25 July to 22 August in Vietnam. There is no leap month in 2024, 2026 or 2027.
Why Vietnamese and Chinese calendars sometimes differ
The calendars use the same rules but different time zones: Vietnam uses UTC+7 since 1968 and China UTC+8. A new moon between 23:00 and midnight Beijing time falls on different local dates, so the months start a day apart. In 1985, Tết fell on 21 January in Vietnam, while Chinese New Year fell on 20 February. Use the Calendar switch to compare them. Vietnam’s zodiac has the water buffalo and cat where China’s has the ox and rabbit.
Tết and other lunar festivals
| Festival | Lunar date | Next solar date |
|---|---|---|
| Lunar New Year (Tết Nguyên Đán) | 1/1 | 17 Feb 2026; 6 Feb 2027 |
| Lantern Festival (Rằm tháng Giêng) | 15/1 | 3 Mar 2026 |
| Hùng Kings’ Day | 10/3 | 26 Apr 2026 |
| Mid-Autumn Festival | 15/8 | 25 Sep 2026 |
| Kitchen Gods’ Day (Ông Công Ông Táo) | 23/12 | 10 Feb 2026; 30 Jan 2027 |
The calendar marks festivals on their computed dates; it does not list public-holiday rules. It highlights day 1 (mùng 1) and day 15 (rằm) of each lunar month, when many families visit pagodas or make offerings.
The 24 solar terms
Solar terms (tiết khí) follow the Sun: one occurs every 15° of solar longitude, about every 15 days. Start of Spring (Lập xuân) falls around 4 February, Clear and Bright (Thanh minh) around 5 April, and Winter Solstice around 21 to 22 December. The table shows the date and time of each term.
Can chi and the zodiac year
Can chi pairs 10 heavenly stems with 12 earthly branches in a 60-step cycle used for years, months and days. The 2026 lunar year is Bính Ngọ (Horse), and 2027 is Đinh Mùi (Goat). The lunar year starts at Tết, not on 1 January.
How the dates are calculated
The calendar calculates dates in your browser for 1900 to 2100. It uses new moons and the Sun’s position from Jean Meeus’s Astronomical Algorithms and calendar rules published by Hồ Ngọc Đức. The results have been checked against known dates for Tết 2024 to 2027 and the 2025 leap month. Times use Vietnam or China time, according to your selection. Use the date calculator to calculate time between dates.
Frequently asked questions
When is Tết 2027?
Tết is on Saturday 6 February 2027, lunar 1/1 in the Đinh Mùi year. The new moon is at 22:56 Vietnam time that day.
What is a leap month (tháng nhuận)?
It is an extra month added about seven times every 19 years to keep the calendar in step with the seasons. It repeats the previous month’s number; 2025 had a leap sixth month.
Why does the Vietnamese lunar calendar sometimes differ from the Chinese one?
Vietnam uses UTC+7 and China UTC+8, so a late evening new moon can fall on different dates. Tết in 1985 was 21 January in Vietnam and 20 February in China. Switch the calendar above to compare dates.
What are mùng 1 and rằm?
They are the first and fifteenth days of each lunar month. The full moon usually falls on day 14 to 16; both days are highlighted in the grid.
How do I convert a lunar birthday to this year’s date?
Use Lunar to solar and enter the lunar day, month and this year. If the birthday is in a leap month that does not exist this year, use the regular month.
Every date, offset and calculation on this page was checked against the sources below.