World Date Formats and Calendar Systems Explained:
Minguo, Buddhist Era, Hijri and More

Why dates look different around the world

When you read a date on a foreign form, receipt or website, three things can differ, and it helps to keep them apart:

The first is about how a date is written; the second is about where the count of years starts; the third is about how the calendar itself is built. The rest of this article keeps these three apart. Japan's era years, such as Reiwa 8 for 2026, are another kind of year numbering; see Japanese Era to Gregorian Year Conversion: Reiwa, Heisei and Showa Explained.

1. Date order: month/day/year, day/month/year or year-month-day

A date such as 03/04/2026 is ambiguous. Read month-first, it is March 4, 2026; read day-first, it is April 3, 2026. The W3C's internationalization guidance notes that MM/DD/YY is unique to the United States (and sometimes used in Canada), that most of Europe uses DD/MM/YY and that Japan uses YY/MM/DD (W3C). Practice still varies by document and service, so do not assume that one country always uses one order. ISO 8601 writes the year first, then month and day, as in 2026-12-31 (ISO); see also What is ISO 8601? and Is 08/09/2026 August 9 or September 8?

2. Taiwan: the Minguo (Republic of China) year

Taiwan uses Minguo years, which count from the founding of the Republic of China. 1912 is Minguo year 1, and January 1 is the founding day (Presidential Office of the Republic of China).

• Minguo year = Gregorian year − 1911
• Gregorian year = Minguo year + 1911
• Example: 2026 − 1911 = Minguo 115

The official year-correspondence table lists Minguo 115 as 2026 and Minguo 1 as 1912 (Household registration table). A date written 115/07/29 in Minguo style can mean July 29, 2026. Years before 1912 are counted as "before Minguo" (民國前), so the formula needs care for those years.

3. Thailand: the Buddhist Era (B.E.)

Thailand commonly uses the Buddhist Era alongside the Gregorian year. Thai government documents label 2026 as B.E. 2569 (Royal Thai Embassy), and a Thai university library page states that year 1 of the Common Era corresponds to B.E. 544 (Chulalongkorn University).

• Buddhist Era = Gregorian year + 543
• Gregorian year = Buddhist Era − 543
• Example: 2026 + 543 = B.E. 2569

This is the common modern conversion for years. Do not apply it to every period: historical sources and religious calendars can follow different rules, and the day on which the Thai year starts has changed over time (the same Chulalongkorn page describes the move of New Year's Day to January 1).

4. The Islamic (Hijri) calendar

The Islamic calendar is a lunar calendar whose first year starts with the Hijra in 622 CE (Princeton University Library). Its months are 29 or 30 days long, and 12 lunar months are on average about 11 days shorter than the Gregorian year (U.S. Naval Observatory). It is connected with religious observances such as Ramadan.

• Because the lunar year is shorter, dates of religious events move earlier by about 11 days each Gregorian year.
• Under the traditional rule, each month begins when the new crescent moon is sighted (U.S. Naval Observatory), so the start of a month can differ between regions.
• There are also calculated variants: tabular calendars, the Umm al-Qura calendar and sighting-based variants (Unicode CLDR). The date you get depends on which variant, and which country, you follow.

Unlike Minguo or Buddhist Era years, you cannot convert a Hijri date by adding or subtracting a fixed number. Check the date in an official calendar of the country or organization concerned.

5. Iran: the Solar Hijri calendar

Do not confuse the Solar Hijri calendar with the lunar Islamic calendar. The Solar Hijri (Shamsi or Khorshidi) calendar is the official calendar of Iran. It is a solar calendar whose year begins at the vernal equinox (Nowruz), and its epoch is also the Hijra of 622 CE (Princeton University Library). The reform that fixed New Year at the vernal equinox is described in Encyclopaedia Iranica.

• It follows the sun, so its dates do not drift against the Gregorian calendar the way lunar Hijri dates do.
• Its year starts in spring, not on January 1, so a single fixed year offset is not enough.
• For an exact conversion, check the date and the calendar's rules, or use an official converter.

6. Ethiopia: the Ethiopian calendar

The Ethiopian calendar has 12 months of 30 days, plus five or six additional days at the end of the year (sometimes called the 13th month, Pagume) (Embassy of Ethiopia). Pagume typically falls between September 6 and 11 (Ethiopian News Agency).

• The Ethiopian year is seven to eight years behind the Gregorian year (Embassy of Ethiopia). Which of the two depends on the time of year.
• The year starts in September, not on January 1.
• Because the months do not line up with Gregorian months, adding or subtracting a fixed number of years does not convert every date correctly.

7. Nepal: the Bikram Sambat (BS) calendar

Nepal uses the Bikram Sambat calendar. The official calendar of Kathmandu Metropolitan City shows Bikram Sambat and Gregorian dates side by side, for example Asoj 2083 as September 17 to October 17, 2026 (Kathmandu Metropolitan City). The Nepal Tourism Board describes Nepali New Year 2083 as Nepal being 57 years ahead of the Western calendar (Nepal Tourism Board).

• BS years are larger than Gregorian years, by roughly 56 to 57 years.
• The BS year does not begin on January 1, so the difference changes during a Gregorian year; for example, September–October 2026 is BS 2083.
• A fixed difference is not enough to convert every date. Check the corresponding date in an official calendar.

8. How to avoid misreading a date from abroad

1. Check the order of the numbers: is it month/day/year, day/month/year or year-month-day? A day above 12 often settles it.
2. Check the year numbering: a year such as 115 or 2569 may be Minguo or Buddhist Era, not Gregorian.
3. Check the calendar system: Hijri, Solar Hijri, Ethiopian and Bikram Sambat are different calendars, not just different year numbers.
4. Check whether the year starts on January 1: if it does not, one fixed offset is not enough.
5. Verify important dates in official sources: for contracts, applications, travel and religious events, confirm the date with the issuing organization or an official calendar.

9. Writing dates in one unambiguous format

When you organize file names and records, a year-month-day format such as yyyyMMdd (for example, 20261231) leaves less room for misreading, and files sort by date when sorted by name. Using one format helps keep your data tidy; it does not convert between calendars. See What is the yyyyMMdd format?

Frequently Asked Questions

References

• W3C Internationalization: Date formats — MM/DD/YY, DD/MM/YY and YY/MM/DD conventions
• ISO: ISO 8601 — Date and time format — the order year, month, day (YYYY-MM-DD)
• Presidential Office of the Republic of China (Taiwan): Introduction — 1912 as Minguo year 1
• Taiwan year-correspondence table (年歲對照表) — Minguo 1 = 1912, Minguo 115 = 2026
• Royal Thai Embassy, Seoul: Official Holidays for 2026 (B.E. 2569) — B.E. 2569 paired with 2026
• Chulalongkorn University Library: history of the Buddhist Era and Thai New Year — Common Era year 1 = B.E. 544; New Year's Day moved to January 1
• U.S. Naval Observatory: The Islamic Calendar — lunar months of 29 or 30 days; months begin with crescent sighting; about 11 days shorter than the civil year
• Unicode CLDR: Islamic calendar types — tabular, Umm al-Qura and sighting-based variants
• Princeton University Library: Calendars (Near Eastern and Islamic Studies guide) — Hijra epoch in 622 CE; Solar Hijri as Iran's official calendar starting at the vernal equinox
• Encyclopaedia Iranica: Calendars ii. In the Islamic period — fixing New Year at the vernal equinox
• Embassy of Ethiopia: The Ethiopian Calendar — 12 months of 30 days plus 5 or 6 days; 7 to 8 years behind
• Ethiopian News Agency: Pagumen, a unifying month of Ethiopia — Pagumen, 6 to 11 September
• Kathmandu Metropolitan City: Calendar (BS / AD) — Asoj 2083 = September 17 – October 17, 2026
• Nepal Tourism Board: Welcome to Nepali New Year 2083 — 57 years ahead of the Western calendar