Image source: Anete Lusina via pexels.com
This final blog posts will briefly examine a few remaining calendars in use today that don’t follow the Gregorian calendar or use slight modifications. In fact, each of these calendars has a vastly unique starting date, usually based on religious reasons, much like the Gregorian calendar.
Iran uses the Persian calendar, also known as the Iranian calendar or Jalaali calendar. This solar calendar is used only in Iran now, but from 2001 to 2022, Afghanistan also used the Persian calendar. However, the Taliban implemented the Hijri lunar calendar, which had also been used during their previous rule from 1996 to 2001.
The Iranian calendar’s start date, or epochal date, begins with Muhammad’s journey from Mecca to Medina in AD 622. This is similar to the Islamic or Hijri calendar we discussed in the last post, but the two calendars have drifted apart by almost 43 years because the Islamic calendar is a lunar calendar while the Iranian calendar is a solar calendar.
To get a very rough estimate of the year when converting from the Iranian calendar, add 621 or 622 to the year on the documents, which will usually be 13xx written in Persian. As an example, ١٣۷۹ (1379) corresponds to approximately 2001 on the Gregorian calendar, depending on the specifically month. It is common for documents to leave off the first two digits for dates in the current century. Iranian year 1404, ۱۴۰۴ (Gregorian year 2025) might be written simply as ۰۴.
While the calendar also uses 12 months and 365-366 days per year, its start date differs from the Gregorian calendar. In 1925, the Iranian calendar was legally adopted, which states that the first day of the year is the first day of spring, or the March equinox. That means New Year’s Day, or Nowruz, falls between March 20 and March 22. The calendar year aligns with the seasons. The first six months is divided into two seasons—spring and summer—of three months each, and each month has 31 days. Autumn or fall has three months of 30 days each. Winter has two month of 30 days, while the final month is 29 days, or 30 days in leap years.
Even though you can calculate an estimated Gregorian date by adding 621 to the Iranian year, since the months and days don’t align with the Gregorian calendar, you would be better off using a calendar date converter. I’ve included some in the Resources section below as I have for all the countries discussed.
Nepal, on the other hand, uses three calendars. The Nepal Sambat (N.S.), or Nepal Era calendar, is primarily used for festivals, rituals, and other social or religious events. While this calendar is used more often in the last decade and is now often included on newspapers and other wide-ranging documents, it is seldom listed on academic or official documents. In contrast, the Gregorian calendar is often used on some academic records, especially at the higher education level.
The official calendar used by school and government functions in Nepal is the Bikram Sambat (B.S.), also known as Vikram Samvat or Bikrami calendar. The new year begins in mid-April on the Gregorian calendar, and each months consists of 29-32 days. The Bikram Sambat is a lunisolar calendar.
As we learned in the last blog post, a lunisolar calendar attempts to coordinate both the solar year and the monthly lunar cycle or phases of the Moon. To maintain the integrity of the lunar month, an extra month is incorporated into the calendar approximately every three years. That way, festivals, season rituals, and holidays still occur during the appropriate season.
Academic records frequently list the Bikram Sambat date followed by the marker “BS” but may also include the Gregorian Calendar date, or Anno Domini, follow by “AD.” An example is as 2074 BS (2018 AD). Furthermore, dates of birth are often listed year/month/day using the BS calendar, followed by day/month/year on the AD calendar, especially for pre-university credentials. Higher education documents are more likely to utilize the Gregorian calendar.
This calendar is approximately 57 years ahead of the Gregorian calendar (56 years and 8 months to be more precise). This is because the Nepali calendar’s origin has been attributed to Indian king Vikramaditya. The Vikram Samvat era began in 57 BCE, when legend says that the king expelled Saka invaders, though history says this battle specific battle was a different king 400 years earlier.
Regardless of the historical basis of the starting year, the calendar is approximately 57 years ahead of the Gregorian calendar. More accurately, it is 56 years and 8 months ahead of the Gregorian calendar. From January to April, it is 56 years ahead; the rest of the year, it is 57 years earlier. While you can subtract 56 or 57 to get a rough estimate, a date converter would be more accurate.
The Ethiopian calendar, in contrast, is a solar calendar, meaning it is aligned with the seasons. It consists of twelve months of 30 days each. A unique feature of the Ethiopian calendar is a 13th month, Pagume, comprised of 5 additional days that has been added as a sort of leap month. The name Pagume comes from the Greek word epagomene, which refers to any days within a solar calendar outside a regular month. Every fourth year, the calendar adds a sixth day to Pagume for the leap year.
The 13-month calendar accounts for the differences between the lunar and solar calendars. While there have been other calendars that used epagomenal days like the Pagume month, such as the Ancient Egyptian calendar and the French Republic calendar, none of the others are still the primary calendar of a country the way the Ethiopian calendar is. However, the Coptic calendar is still used for farming and religious reasons, and the Jewish calendar discussed below sometimes includes an intercalary month.
The first day of the Ethiopian calendar year aligns with September 11th (or September 12th in leap years) on the Gregorian calendar, which is the start of spring in Ethiopia. Even though the Ethiopian calendar is also 365 days, the Ethiopian calendar is 7-8 years (7 years, 8 months) behind the Gregorian. This is due to a difference in the the Ethiopian Orthodox Church’s calculations of the birth year of Jesus Christ compared to the Catholic Church’s calculations.
While you can add 8 years to the Ethiopian calendar to convert to the Gregorian calendar, a date converter would be more accurate. Many academic records from Ethiopia list both the Ethiopian Calendar year (often designated as E.C.) and the Gregorian year (often placed in parentheses). As an interesting aside, Ethiopian Time also differs from the 24-hour clock used in most of the world, but that’s outside the scope of this blog.
Finally, let’s wrap up this surprisingly lengthy review of calendar systems with a brief discussion of Israel and the Hebrew calendar, also known as the Jewish calendar. This is another lunisolar calendar, meaning months are based on lunar months while years are based on solar years. An additional “leap month” is added at specified intervals seven times in a 19-year cycle known as the Metonic cycle.
While the Gregorian calendar designates the years since the birth of Jesus Christ, Hebrew years are counted according to the Jewish date of Creation. According to this calculation, the Jewish calendar began in September 3761 BCE, meaning the Jewish calendar is 3760-3761 years older than the Gregorian calendar date. You can add 3761 to get a rough estimate, or use a date converter.
The Jewish calendar is used alongside the Gregorian calendar, and it is common for official documents and academic records to include both dates. Hebrew dates are often written right-to-left with the day of the month, followed by the name of the month, and then the Hebrew year. Translations may follow this format or may list the date in year, month, date order.
There’s another interesting note about dates on official documents. When specifying years (of the Hebrew calendar) in the current millennium, it is common for the date to exclude the first digit (the thousands column). For example, the Hebrew year 5782 is written as 782 (תשפ״ב) rather than 5782 (ה׳תשפ״ב). This is somewhat similar to how Gregorian documents will often list only the last two digits of the year, 25 instead of 2025, for example.
I hope you have enjoyed this whirlwind tour of calendar and dating systems used worldwide. More than that, I hope this series of blog posts helped you learn something new, interesting, and useful. Stay tuned for the next blog entry, which will be a return to specific educational credentials.
Resources:
Afghan Date Converter. Afghan Date Converter. https://www.afghandateconverter.com/
Bikram Sambat Nepali Calendar-Based on Ministry of Information. Nepali Calendar. https://nepalicalendar.rat32.com/
Calendar, and the Chinese Calendar. Emory Libraries. https://guides.libraries.emory.edu/c.php?g=1457269&p=10835095
Calendar Converter for Near East Historians. Muqawwim.com. https://www.muqawwim.com/
Calendars: the Solar Hijri Calendar, the Islamic (Hijri) Calendar, the Gregorian Calendar, the Hebrew
A Concise Review of the Iranian Calendar. Astrophysics, 2004. https://arxiv.org/abs/astro-ph/0409620 and http://aramis.obspm.fr/~heydari/divers/ir-cal-eng.html
Differences Between Gregorian Calendar and Jewish Calendar Systems. Galilee Calendars. https://www.galileecalendarcompany.com/differences-between-gregorian-calendar-and-jewish-calendar-systems%E2%80%A8/
Ethiopian Calendar Converter. Time.et. https://time.et/convert
Ethiopia Celebrates New Year 7 Years behind the Gregorian Calendar. The Africa Report, 2011. https://www.theafricareport.com/8355/ethiopia-celebrates-new-year-7-years-behind-gregorian-calendar/
Ethiopia: The Country Where a Year Lasts 13 Months. BBC News, 2021. https://www.bbc.com/news/world-africa-57443424
Hebrew Calculator. HebCal. https://www.hebcal.com/converter?gd=20&gm=6&gy=2025&g2h=1
History of Bikram Sambat Nepali Calendar. Ashesh.com. https://www.ashesh.com.np/bikram-sambat-nepali-calendar-history/
Iranian Calendar Converter. Iran Chamber Society. https://www.iranchamber.com/calendar/converter/iranian_calendar_converter.php
Islamic Calendar in Afghanistan. Hijria.com. https://www.hijria.com/en/hijri-gregorian-calendar/afghanistan/
The Iranian Calendar is Perfect… and Here’s Why. My Persian Corner. https://www.mypersiancorner.com/the-iranian-calendar-is-perfect-heres-why/
It’s about Time. Chabad.org. https://www.chabad.org/library/article_cdo/aid/407511/jewish/Its-About-Time.htm
Jewish Holidays & Festivals: The Jewish Calendar: An Overview. Jewish Virtual Library. https://www.jewishvirtuallibrary.org/the-jewish-calendar
Jewish Religious Year. Britannica. https://www.britannica.com/topic/Jewish-religious-year#ref1290566
Nepal Sambat Converter. Subhash. https://www.hijria.com/en/hijri-gregorian-calendar/afghanistan/
“Pagume” The 13th Month of Geez Calendar. Ministry of Information, Eritrea. https://shabait.com/2019/09/21/pagume-the-13th-month-of-the-geez-calendar/
Persian Calendar and Converter. ParsTimes. https://www.parstimes.com/persian/calendar/
The Persian Calendar for 3000 years. Earth, Moon, and Planets, 1996. https://www.astro.uni.torun.pl/~kb/Papers/EMP/PersianC-EMP.htm
The Persian Calendar (Solar Hijri Calendar). Welcome to Iran. https://welcometoiran.com/persian-calendar-solar-hijri/
Persian Online: Grammar & Resources: Calendar. Univeristy of Texas at Austin. https://sites.la.utexas.edu/persian_online_resources/numbers-1/calendar/
Rajan Nepal’s Date Converter. Rajan.com. https://www.rajan.com/calendar/default.asp
Solar Hijri Calendar. Wikipedia. https://en.wikipedia.org/wiki/Solar_Hijri_calendar
Taliban Changes Solar Year to Hijri Lunar Calendar. 8AmMedia. https://8am.media/eng/taliban-changes-solar-year-to-hijri-lunar-calendar/
Why Ethiopia Uses a 13-Month Calendar: Learn the Fascinating Reasons. Amero Media, 2025. https://aemeromedia.com/why-does-ethiopia-have-13-months/