Quick answer
Pick a Gregorian date to see its Vietnamese lunar date, the stem-branch names of the day, month and year, the solar term, whether it is an auspicious day, and its six lucky hours. Switch to “Lunar → Solar” to find the Gregorian date of a lunar date, leap months included. Calculations use Vietnam time (UTC+7) and cover 1900–2100.
How does the Vietnamese lunar calendar work?
The Vietnamese calendar (âm lịch) is lunisolar: months follow the Moon, years follow the Sun, and an extra leap month is inserted now and then to keep the seasons in place. This tool computes everything from astronomical formulas (new moons and the Sun's position) instead of a printed table, so it handles any date across two centuries, including rare cases such as the leap 11th month of 2033. Click a day in the month view to see its details.
How to convert dates
- 1
The tool opens on today. To check another day, use the “Gregorian date” field or click a day in the month view.
- 2
Read the result: the lunar date (marked “leap” in a leap month), the stem-branch names of the day, month and year, the solar term, the day type and the six auspicious hours.
- 3
To find the Gregorian date of a lunar date (an anniversary, a lunar birthday, a full-moon day), choose “Lunar → Solar” and enter the lunar day, month and year. If that year has a leap month with the same number, tick “Leap month” when needed.
- 4
Use ‹ › above the month view to move between months. The 1st and 15th lunar days are in red, a green dot marks auspicious days and today has a blue outline.
- 5
The last line counts the days to the next Lunar New Year (Tết).
Upcoming Lunar New Year dates (Vietnam)
The first day of the first lunar month, computed with this tool in Vietnam time.
| Year | Stem-branch | Tết (Gregorian) | Leap month that year |
|---|---|---|---|
| 2025 | Ất Tỵ (Snake) | Wed 29 Jan 2025 | Leap 6th month |
| 2026 | Bính Ngọ (Horse) | Tue 17 Feb 2026 | None |
| 2027 | Đinh Mùi (Goat) | Sat 6 Feb 2027 | None |
| 2028 | Mậu Thân (Monkey) | Wed 26 Jan 2028 | Leap 5th month |
| 2029 | Kỷ Dậu (Rooster) | Tue 13 Feb 2029 | None |
| 2030 | Canh Tuất (Dog) | Sat 2 Feb 2030 | None |
| 2031 | Tân Hợi (Pig) | Thu 23 Jan 2031 | Leap 3rd month |
Swipe sideways to see the whole table →
Tết 2030 falls on 2 February in Vietnam but 3 February in China: the new moon is at 23:08 on 2 February in Hanoi, which is already 00:08 on 3 February in Beijing.
The 12 two-hour periods
Each traditional hour lasts two clock hours. Every day has six auspicious hours, depending on the day's earthly branch.
| Hour | Zodiac animal | Clock time |
|---|---|---|
| Tý | Rat | 23:00 – 01:00 |
| Sửu | Ox | 01:00 – 03:00 |
| Dần | Tiger | 03:00 – 05:00 |
| Mão | Cat (Vietnam) / Rabbit | 05:00 – 07:00 |
| Thìn | Dragon | 07:00 – 09:00 |
| Tỵ | Snake | 09:00 – 11:00 |
| Ngọ | Horse | 11:00 – 13:00 |
| Mùi | Goat | 13:00 – 15:00 |
| Thân | Monkey | 15:00 – 17:00 |
| Dậu | Rooster | 17:00 – 19:00 |
| Tuất | Dog | 19:00 – 21:00 |
| Hợi | Pig | 21:00 – 23:00 |
The 24 solar terms in 2026
Solar terms split the Sun's yearly path into 24 steps of 15°, so they land on nearly the same Gregorian dates every year.
| Solar term | Starts | Solar term | Starts |
|---|---|---|---|
| Minor Cold (Tiểu hàn) | 5 Jan | Minor Heat (Tiểu thử) | 7 Jul |
| Major Cold (Đại hàn) | 20 Jan | Major Heat (Đại thử) | 23 Jul |
| Start of Spring (Lập xuân) | 4 Feb | Start of Autumn (Lập thu) | 7 Aug |
| Rain Water (Vũ thủy) | 18 Feb | End of Heat (Xử thử) | 23 Aug |
| Awakening of Insects (Kinh trập) | 5 Mar | White Dew (Bạch lộ) | 7 Sep |
| Spring Equinox (Xuân phân) | 20 Mar | Autumn Equinox (Thu phân) | 23 Sep |
| Clear and Bright (Thanh minh) | 5 Apr | Cold Dew (Hàn lộ) | 8 Oct |
| Grain Rain (Cốc vũ) | 20 Apr | Frost's Descent (Sương giáng) | 23 Oct |
| Start of Summer (Lập hạ) | 5 May | Start of Winter (Lập đông) | 7 Nov |
| Grain Buds (Tiểu mãn) | 21 May | Minor Snow (Tiểu tuyết) | 22 Nov |
| Grain in Ear (Mang chủng) | 5 Jun | Major Snow (Đại tuyết) | 7 Dec |
| Summer Solstice (Hạ chí) | 21 Jun | Winter Solstice (Đông chí) | 22 Dec |
Swipe sideways to see the whole table →
Examples
A death anniversary (giỗ)
A grandparent died on the 10th day of the 3rd lunar month: choose “Lunar → Solar”, enter 10, month 3, year 2027 and you get 16 April 2027. Change the year for the next one.
When is the Mid-Autumn Festival?
The 15th day of the 8th lunar month in 2026 is 25 September 2026. The first full moon of 2027 (Rằm tháng Giêng) is 20 February 2027.
Lunar birthdays in a leap year
2025 has a leap 6th month: lunar 1/6 is 25 June 2025 and leap 1/6 is 25 July 2025. People born in a leap month usually celebrate in the regular month in non-leap years.
Counting down to Tết
On 21 October 2026 there are 108 days to Tết Đinh Mùi (6 February 2027). The countdown is recalculated from today's date on your device.
Common problems
- Lunar → Solar says the date doesn't exist.
- Short lunar months have only 29 days, so day 30 doesn't exist; or you ticked “Leap month” for a month that isn't a leap month that year. Untick it or pick day 29.
- The lunar date is one day off from a Chinese calendar or another app.
- The Vietnamese calendar uses Hanoi time (UTC+7), the Chinese one Beijing time (UTC+8). When a new moon falls between 23:00 and midnight, months can start a day apart, and occasionally the leap month moves too (Tết 1985 is a famous case).
- Dates before 1968 don't match calendars printed at the time.
- The tool uses UTC+7 for every year. Before 1968, Vietnamese almanacs often followed Beijing time, so a few month starts may differ by a day.
- It won't accept 1899 or 2101.
- The astronomical formulas are verified for 1900–2100, so dates outside that range are rejected rather than risking wrong results.
- Lucky hours differ from another almanac.
- There are several traditions for choosing days. The tool uses the most common table of auspicious hours and the 12 day officers; treat it as cultural reference, not astronomy.
How the lunar calendar is calculated
Each lunar month starts on the day of the new moon, so months last 29 or 30 days. A lunar year usually has 12 months (354–355 days), about 11 days shorter than a solar year, so roughly 7 leap months are added every 19 years to keep Tết in late winter or early spring.
The 11th lunar month always contains the winter solstice. When there are 13 new moons between two 11th months, the year gets a leap month: the first month without a principal solar term, numbered after the month before it.
The tool implements Hồ Ngọc Đức's algorithm (“Âm lịch Việt Nam”), based on the formulas in Jean Meeus's Astronomical Algorithms, in UTC+7. Every day from 1900 to 2100 has been checked to round-trip from solar to lunar and back to the same date.
Stem-branch names and lucky days
Stem-branch names pair the 10 heavenly stems (Giáp, Ất, Bính…) with the 12 earthly branches (Tý, Sửu, Dần…) in a 60-step cycle. Years, months, days and hours each have one: 2026 is Bính Ngọ, the Year of the Horse, and the first lunar month is always a Dần (Tiger) month. Vietnam uses the Cat instead of the Rabbit.
Auspicious (hoàng đạo) and inauspicious (hắc đạo) days come from the lunar month and the day's branch, following the 12 day officers of the traditional almanac. They are a cultural custom and shown for reference only.
Glossary
- New moon (Sóc)
- The moment the Moon sits between Earth and the Sun; the day containing it is day 1 of the lunar month.
- Long / short month
- A 30-day lunar month is long (đủ), a 29-day one is short (thiếu).
- Leap month
- An extra month in a 13-month lunar year, numbered after the month before it, e.g. “leap 6th month”.
- Principal term
- Twelve of the 24 solar terms (winter solstice, Major Cold, Rain Water…); a month without one becomes the leap month.
- Stem-branch (can chi)
- Naming years, months, days and hours with a heavenly stem and an earthly branch, repeating every 60.
- Auspicious hours
- Six of the twelve two-hour periods in each day considered favourable by the almanac.
Frequently asked questions
Is the Vietnamese lunar calendar the same as the Chinese one?
Same rules, different time zone: Vietnam uses UTC+7 and China UTC+8, so new months or leap months occasionally differ. Tết 1985 was on 21 January in Vietnam but 20 February in China.
Which years are supported?
1900 to 2100, in both directions.
How can I tell if a year has a leap month?
Choose “Lunar → Solar” and type the year: the tool says which month is the leap month, if any. 2025 has a leap 6th month and 2028 a leap 5th month.
Why do some lunar months have a 30th day and others don't?
A lunar month runs from one new moon to the next, about 29.53 days, so months alternate between 29 and 30 days.
Where does “today” come from?
Your device's clock. If it is set to a time zone far from Vietnam, “today” may differ by a day late at night or early in the morning.
Do you store the dates I look up?
No. Everything is calculated in your browser and nothing is sent anywhere.
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