Buddhist calendar

The Buddhist calendar is a set of lunisolar calendars used in many countries such as Tibet, Cambodia, Laos, Myanmar, Bangladesh, India, Sri Lanka, Thailand, and Vietnam, as well as in Malaysia and Singapore. It is also used by Chinese populations for special events and religious holidays. Although these calendars share similar roots, they have small but important differences.

In Thailand, the Buddhist Era is a special way to count years that is used alongside both the traditional Thai lunar calendar and the Thai solar calendar. Most Southeast Asian lunisolar calendars are based on an older form of the Hindu calendar.

Today, the traditional Buddhist lunisolar calendar is mostly used for celebrating Theravada Buddhist festivals. In Thailand, the Thai Buddhist Era, which is simply a changed version of the Gregorian calendar, is used as the official way to keep track of dates.

Structure

The Buddhist calendar is used in many countries, like Tibet, Cambodia, Laos, Myanmar, Bangladesh, India, Sri Lanka, Thailand, Vietnam, Malaysia, and Singapore. It is used for religious and special events. These calendars share some parts but have their own special features.

The calendar is based on the Moon and the Sun. This helps match lunar months to the solar year. A normal lunar year has 354 days, which is shorter than a solar year of about 365.25 days. Extra months and days are added in some years to keep the calendar aligned. The new year usually starts around April, but the exact date changes in different places. Some countries, like Thailand and Cambodia, no longer use the old calendar for New Year.

Sri Lankan Theravada tradition starts Buddha Varsa on 16 April 545 BCE. In all Theravada traditions, the calendar’s epoch was the day the Buddha attained parinibbāna. Not all traditions agree on the exact date. In Burmese Buddhist tradition, it was 13 May 544 BCE. In Thai Buddhist tradition, it was 11 March 544 BCE. As of 2026, the Buddhist new year begins on 21 May 2026 in most places, but on 1 January 2026 in Thailand and on 18 February 2026 in Tibet.

The calendar has two types of months: synodic month and sidereal month. Synodic months make up the years. The 27 lunar sidereal days, called nakshatra, are used for astrology along with the 12 signs of the zodiac.

Because a Synodic lunar month is about 29.5 days, the calendar uses months that are 29 and 30 days long, taking turns.

The Buddhist calendar is a lunisolar calendar. Its months are based on lunar months and its years are based on solar years. It aims to keep the lunar part matched to the solar part. A normal lunar year has 354 days, while a solar year has about 365.25 days. So, extra months are added to the lunar year.

The Cambodian, Lao, and Thai systems give animal names to years in a 12-year cycle.

The Cambodian calendar also has a 10-year naming cycle. Cambodians use different systems to name a year. For example, 2017 is called 2561 Buddhist Era, the year of the Rooster, Nuppasak (Year 9). The Thai lunar calendar also uses a similar 10-year cycle.

Accuracy

See also: Burmese calendar § Accuracy

Buddhist calendars in Southeast Asia use lunar months but try to match the solar year. They add extra months and days to stay close to the solar year. However, these calendars are based on a sidereal year, which is a little longer than the actual solar year. Because of this, the calendars slowly move away from the real seasons. They shift about one day every 60 years and four months.

Because of this shift, the New Year's Day, which used to be on March 22, now falls on April 17. Thailand has changed its "Buddhist Era" to match the Gregorian calendar, called the Thai solar calendar. In Myanmar, calendar experts try to fix the problem by changing when they add extra months, but this makes it hard to plan calendars far into the future.

History

The Buddhist Era began in Southeast Asia when Buddhism arrived in the early years after year zero. It used the old ways of counting years but changed how the years were marked. First, the Saka Era was used, starting around 80 CE. Later, the Burmese Era began in Myanmar in 640 CE and spread to other places.

In Thailand, the Buddhist Era changed in 1912 when King Vajiravudh decided it would follow the Thai solar calendar, starting on April 1. In 1940, it was changed again so the year would start on January 1. Today, the Thai Buddhist Era is 543 years ahead of the Common Era.

Current usage

The lunisolar calendar helps mark important Buddhist holidays. Many of these holidays are also celebrated as public holidays in many places.

Computer support

The Thai-style Buddhist calendar adds the Buddhist era to the Gregorian calendar. It is supported in Java 8, iOS, and macOS. These systems can use this special calendar for dates.