This is about the solar Ottoman calendar based on the Julian calendar. For the lunar Hijri calendar see Islamic calendar.

The Rumi calendar (Turkish: Rumi takvim), a specific calendar based on the Julian calendar but starting with the year of Muhammad's emigration (Hijra) in 622 AD, was officially used by the Ottoman Empire after Tanzimat (1839) and by its successor, the Republic of Turkey until 1926. It was adopted for civic matters and is a solar based calendar, assigning a date to each solar day.

[edit] History

In the Islamic state of Ottoman Empire, the religious Islamic calendar was in use, of which days are numbered within each lunar phase cycle. Because the length of the lunar month is not an even fraction of the length of the tropical year, a purely lunar calendar quickly drifts against the seasons.

In 1677, Head treasurer (Turkish: Baş defterdar) Hasan Pasha of Sultan Mehmed IV proposed the correction of financial records by dropping one year (escape year)every 33 years resulting from the difference between the lunar Islamic calendar and the solar Julian calendar.^[1]

In 1740 (1152 AH) during the reign of Sultan Mahmud I, March was adopted as the first month of the fiscal year for the payment of taxes and dealings with government officials instead of Muharram following Treasurer Atıf Efendi's proposal.^[1]

Proposed by Treasurer Moralı Osman Efendi during the reign of Sultan Abdul Hamid I, the range of the fiscal calendar applications was extended in 1794 to state expenditures and payments in order to prevent surplus cost arising from the time difference between the Islamic and Julian calendar.^[1]

The Julian calendar, used from 1677 AD on for fiscal matters only, was adopted on March 13, 1840 AD (March 1, 1256 AH), in the frame of Tanzimat reforms shortly after the ascension to the throne of Sultan Abdülmecid I, as the official calendar for all civic matters and named "Rumi calendar" (literally Roman calendar).^[1] The counting of years began with the year 622 AD, when Muhammad and his followers emigrated from Mecca to Medina, the same event that also Islamic calendar started. The months and days of the Julian calendar were used, the year starting in March.^[2] However, in 1256 AH the difference between the Hijri and the Gregorian calendars amounted 584 years. With the switching over from lunar calendar to solar calendar, the difference between the Rumi calendar and the Gregorian calendar remained constant 584 years.

In order to facilitate easy conversion, the difference of thirteen days between the Rumi calendar and the Gregorian calendar was eliminated in February 1917. The Julian calendar was abandoned on February 16, 1332 AH, leaving the difference of 584 years unchanged, however. Thus, February 16, 1332 AH (February 1917 AD) suddenly became March 1, 1333 AH (March 1, 1917 AD) and the year 1333 AH (1917 AD) was made into a year with only ten months, running from March 1 to December 31. January 1, 1334 AH thus became January 1, 1918 AD.^[3]

The Rumi calendar remained in use until the dissolution of the Ottoman Empire and in the first years of the succeeding Republic of Turkey as well. It was abandoned by an act on December 26, 1341 AH (1925 AD) as part of Atatürk's reforms and was replaced by the Gregorian calendar.^[4] The Ottoman language names of the four months of the Rumi calendar, taken over to the Turkish Gregorian calendar, Teşrin-i Evvel, Teşrin-i Sânî, Kânûn-ı Evvel and Kânûn-ı Sânî, were changed on January 10, 1945 to Turkish language ones, Ekim, Kasım, Aralık and Ocak. March 1 as the beginning of the fiscal year was used until 1981.

[edit] Dual date

In the Ottoman Empire, the lunar-based Hijri calendar remained in use for religious matters alongside the Rumi calendar. In order to prevent confusion between the dates, both calendars were used on most documents.

[edit] Conversion between the Rumi and Gregorian calendars

By the date conversion between the two calendars, following periods have to be taken in consideration:

• Before March 13, 1840 AD

No conversion is possible, since Rumi calendar was not in use.

• Between March 13, 1840 AD (March 1, 1256 AH) and February 28, 1917 AD (February 15, 1333 AH)

Add 13 days and 584 years to find Gregorian date.

• After March 1, 1917 AD (March 1, 1333 AH)

Add 584 years only.

From Rumi calendar into Gregorian calendar

31 March Incident occurred on March 31, 1325 AH
Adding 13 days to date and 584 to year: April 13, 1909 AD

From Gregorian calendar into Rumi calendar

Proclamation of the republic in Turkey on October 29, 1923 AD
Subract 584 from year. Date remains same after January 1, 1918 due to use of the Gregorian calendar in the Rumi calendar: October 29, 1339 AH

[edit] Date converters

• Computus Calendar Conversion Program

[edit] See also

• List of calendars

[edit] References