TL;DR: Phật Đản has two dates because two traditions count differently: Northern Buddhism in Vietnam, China, Korea and Japan used to commemorate it on the 8th day of the fourth lunar month, while Southern Buddhism takes the full moon day of the month of Vesak, that is the full moon of the fourth month. The agreed milestone of adopting the full moon day is recorded differently by the sources: 1950 according to Venerable Thích Trí Chơn, 1960 in Cambodia according to VTC News. In 1999 the United Nations recognised the Day of Vesak. The Vietnam Buddhist Sangha holds Buddha's Birthday Week from the 8th to the full moon of the fourth month, with the official ceremony on the full moon day.
Why Does Buddha's Birthday Have Two Dates: the 8th and the 15th of the Fourth Lunar Month?
Buddha's Birthday has two dates because two Buddhist traditions reckon the day of birth differently. According to Venerable Thích Trí Chơn, Southern Buddhism calls the festival Vesak, also the Triple Event, holding that the Buddha was born, attained enlightenment and entered parinirvana all in the month of Vesak; Northern Buddhism holds that the Buddha was born in the fourth month, entered parinirvana in the second lunar month and attained enlightenment in the twelfth, and so takes the 8th day of the fourth month as the day of birth[1]. VTC News writes that Buddhists in Vietnam and in some countries influenced by Northern Buddhism, such as China, Korea and Japan, formerly marked Buddha's Birthday on the 8th day of the fourth lunar month, while for Southern Buddhism and Tibetan Buddhism this is the day of the Triple Event[2].
The name Vesak comes from the Sanskrit Vaiśākha, the name of the second month in the ancient Indian calendar, corresponding to the fourth lunar month. According to tradition, the Buddha appeared on the full moon day of this month[2].
On when the date was unified, two sources differ. Venerable Thích Trí Chơn, speaking to Thanh Niên newspaper, says that in 1950 the congress of the World Fellowship of Buddhists gathered 26 countries, Vietnam among them, to found the Fellowship and recognized the full moon day of the fourth month as the day of the Buddha's birth[1]. VTC News instead records that in 1960 the World Buddhist Congress, meeting in Cambodia, agreed to take the 15th day of the fourth month as Buddha's Birthday for Buddhists worldwide[2].
What Are Vesak and the United Nations Celebration?
Vesak is the international name of Buddha's Birthday, from the Sanskrit Vaiśākha[2]. According to the VietnamPlus report on the 2026 Vesak announcement, the Buddha's birthday is observed annually by the United Nations as a world religious festival honoring the humanistic values of Buddhism for the peace of humankind[3].
On 15 December 1999 the United Nations General Assembly adopted Resolution 54/115, giving international recognition to the Day of Vesak[4]. VTC News records that the resolution came at the 54th session and recognized the day of the Buddha's Triple Event, the full moon of the fourth lunar month, as the day of the United Nations Day of Vesak celebration[2]. Vietnam has hosted the United Nations Day of Vesak four times, in 2008, 2014, 2019 and 2025[4].
How Does the Vietnam Buddhist Sangha Organize Vesak Week?
According to the VietnamPlus report, the announcement on the Vesak celebration of Buddhist year 2570, signed by Most Venerable Thích Thiện Nhơn, Chairman of the Executive Council of the Vietnam Buddhist Sangha, proposes holding the commemoration from the 1st day of the fourth month of the Bính Ngọ year, that is, May 17, 2026. Vesak Week runs from the 8th to the 15th of the fourth month of the Bính Ngọ year, that is, May 24 to May 31, 2026, and the main ceremony is held on the 15th of the fourth month, falling on May 31, 2026[3].
The central altar is set up at the Office of the provincial or municipal Executive Board of the Vietnam Buddhist Sangha or at other suitable locations. The celebration includes the Vesak message of the Most Venerable Supreme Patriarch, the address of the Most Venerable Deputy Supreme Patriarch and Chairman of the Executive Council, and a sermon on the meaning of Vesak by the Central Dharma Propagation Board; temples set up the traditional Buddha bathing basin[3]. On the afternoon of May 24, 2026, the Executive Board of the Vietnam Buddhist Sangha in Lâm Đồng province held the lighting of seven lotus flowers on the Cà Ty river, Phan Thiết ward[4].
What Do the Buddha Bathing Rite and the Flower Offering Ritual Mean?
The Thanh Niên article writes that the Vesak celebration is an occasion to honor the Buddha and to recall his life as a historical person together with his teachings. On the Buddha bathing rite, Venerable Thích Trí Chơn describes everyone present ladling water over the image of the infant Buddha, and explains that in doing so the person contemplates bathing themselves so that the mind becomes clean[1].
For Buddhists with a Buddha altar at home, the Venerable lists six offerings in Buddhist ritual: incense, lamps, flowers, food offerings, fruit and music; flowers speak of fragrance and a person's virtue, while the food offerings (đồ, an old word) are items such as sticky rice, sweet soup and tea[1].
Comparison Table of the Two Traditions of Organizing Buddha's Birthday
| Criterion | Northern tradition | Southern tradition |
|---|---|---|
| Traditional date | 8th day of the fourth lunar month | Full moon of Vesak, the 15th of the fourth lunar month |
| Places named in the sources | Vietnam, China, Korea, Japan (formerly) | Countries of Southern Buddhism; Tibetan Buddhism also regards it as the Triple Event day |
| Meaning of the festival | Commemoration of birth | Birth, enlightenment and parinirvana, called the Triple Event |
| Reckoning of the three events | Birth in the fourth month, parinirvana in the second, enlightenment in the twelfth | All three in the month of Vesak |
Why Is the Main Festival Day in Vietnam Now the 15th of the Fourth Lunar Month?
According to Venerable Thích Trí Chơn, Vietnam's tradition was to mark the Buddha's birth on the 8th day of the fourth lunar month; after the full moon day of the fourth month was recognized, Vietnamese Buddhism took the full moon as the main day and, to combine it with tradition, introduced a Vesak season running from the 8th to the full moon of the fourth month[1]. The 2026 announcement likewise sets Vesak Week from the 8th to the 15th of the fourth month, with the main ceremony on the 15th[3].
The VietnamPlus article writes that the Vesak celebration in Vietnam is held solemnly and has become a festival shared by the whole community, and sees in this an affirmation of the policy of respecting and ensuring freedom of belief and religion[4].
How Do Other Countries Organize Buddha's Birthday?
VTC News writes that people in countries of Southern Buddhism usually hold the festival on the full moon of the fourth lunar month, or of May in the solar calendar[2].
In 2007, May had two full moons, so some places held Buddha's Birthday on the first full moon (May 1) and others chose the second (May 31)[2].
Nhật Nguyệt's Suggestions
When looking up the date of Buddha's Birthday, find out whether the place you attend follows the 8th or the full moon of the fourth lunar month. In Vietnam, the annual announcement of the Vietnam Buddhist Sangha states the main day and Vesak Week; the solar date changes every year. At international events the festival usually goes by the name Vesak.
